MSP430FR5994: Not getting constant speed in SPI

#include <msp430.h>
#include <stdio.h>
#include "lmk04832.h"

#define MSP430_CPU_CLK_HZ      (20000000 / 2)
#define FAIL            (-1)
#define TRUE            (1)
int timeCount = 0;

void spiInit()
{
    /* Configure GPIO */
    P4SEL1 &= (~BIT7);
    P4SEL0 &= (~BIT7);
    P4OUT &= ~BIT7;
    P4DIR |= BIT7;

    /* USCI_B1 SCLK, MOSI, and MISO pin */
    P5SEL1 &= ~(BIT0 | BIT1 | BIT2);
    P5SEL0 |= (BIT0 | BIT1 | BIT2);
}

void clockInit()
{
    // XT1 Setup
    CSCTL0_H = CSKEY_H;                     // Unlock CS registers
    CSCTL1 = DCOFSEL_0;                     // Set DCO to 5.33MHz
    CSCTL2 = SELA__LFXTCLK | SELS__DCOCLK | SELM__DCOCLK;
    CSCTL3 = DIVA__1 | DIVS__32 | DIVM__1;   // set all dividers
    CSCTL0_H = 0;                           // Lock CS registers

    // Configure USCI_B1 for SPI operation
    UCB1CTLW0 = UCSWRST;                    // **Put state machine in reset**
    UCB1CTLW0 |= UCMST | UCSYNC | UCMSB | UCSSEL__SMCLK | UCCKPH; // 3-pin, 8-bit SPI master
                                            // Clock polarity high, MSB
    UCB1BRW = 0x00;                         // 2
    //UCB1MCTLW = 0;                          // No modulation
    UCB1CTLW0 &= ~UCSWRST;                  // **Initialize USCI state machine**
}

char spiWrite(void)
{
    int size = 0;
    unsigned int i;
    char addr1, addr2, txData;

    size = sizeof(lmkRegVal)/sizeof(lmkRegVal[0]);
    for(i = 0; i<= size; i++)
    {
        printf("Transferred %d byte \n\r",i);
        /* CS line low */
        P4OUT &= ~BIT7;

        addr1 = (lmkRegVal[i] & 0xFF0000)>>16;

        timeCount = 500;
        while((!(UCB1IFG & UCTXIFG)) && (0 < timeCount))
        {
            /* Wait for 1 msec */
            __delay_cycles(MSP430_CPU_CLK_HZ / 1000);
            timeCount--;
        }
        /* Check for time out error */
        if(0 == timeCount)
            return FAIL;
        else
        {
            /* Transmit R/W and A14-A8 bits */
            UCB1TXBUF = addr1;                   // Load reg addr
        }

        addr2 = (lmkRegVal[i] & 0x00FF00)>>8;
        timeCount = 500;
        while((!(UCB1IFG & UCTXIFG)) && (0 < timeCount))
        {
            /* Wait for 1 msec */
            __delay_cycles(MSP430_CPU_CLK_HZ / 1000);
            timeCount--;
        }
        /* Check for time out error */
        if(0 == timeCount)
            return FAIL;
        else
        {
            /* Transmit A7-A0 bits */
            UCB1TXBUF = addr2;                   // Load reg addr
        }

        txData = (lmkRegVal[i] & 0x0000FF);
        timeCount = 500;
        while((!(UCB1IFG & UCTXIFG)) && (0 < timeCount))
        {
            /* Wait for 1 msec */
            __delay_cycles(MSP430_CPU_CLK_HZ / 1000);
            timeCount--;
        }
        /* Check for time out error */
        if(0 == timeCount)
            return FAIL;
        else
        {
            /* Transmit D7-D0 bits */
            UCB1TXBUF = txData;                   // Load reg addr
        }
        /* CS line High */
        P4OUT |= BIT7;
    }
}

char spiRead(void)
{
    char addr1, addr2, rxData1, rxData2;
    addr1 = 0x0B // Read register;
    P4OUT &= ~BIT7; // CS low

    timeCount = 500;
    while((!(UCB1IFG & UCTXIFG)) && (0 < timeCount))
    {
        /* Wait for 1 msec */
        __delay_cycles(MSP430_CPU_CLK_HZ / 1000);
        timeCount--;
    }
    /* Check for time out error */
    if(0 == timeCount)
        return FAIL;
    else
    {
        /* Transmit R/W and A14-A8 bits */
        UCB1TXBUF = addr1;                   // Load reg addr
    }

    addr2 = 0x00;
    timeCount = 500;
    while((!(UCB1IFG & UCTXIFG)) && (0 < timeCount))
    {
        /* Wait for 1 msec */
        __delay_cycles(MSP430_CPU_CLK_HZ / 1000);
        timeCount--;
    }
    /* Check for time out error */
    if(0 == timeCount)
        return FAIL;
    else
    {
        /* Transmit A7-A0 bits */
        UCB1TXBUF = addr2;                   // Load reg addr
    }

//    while(!(UCB1IFG&UCRXIFG));
    rxData1 = UCB1RXBUF;

    rxData1 = rxData1 << 6;

//    while(!(UCB1IFG&UCRXIFG));
    rxData2 = UCB1RXBUF;
    P4OUT |= BIT7;

    rxData1 = rxData1 | rxData2;

    return rxData1;
}
int main(void)
{
    printf("Inside main \n\r");

    char rxData, checkdata;

    WDTCTL = WDTPW | WDTHOLD;               // Stop watchdog timer

    // Disable the GPIO power-on default high-impedance mode to activate
    // previously configured port settings
    PM5CTL0 &= ~LOCKLPM5;

    spiInit();
    clockInit();

//    checkdata = spiWrite();
    if(checkdata == FAIL)
    {
        printf("Transmision not successful \n\r");
    }
    else
    {
        printf("Transmission successful \n\r");
    }

    rxData = spiRead();
    if(rxData == FAIL)
    {
        printf("Transmision not successful \n\r");
    }
    else
    {
        printf("Data = %x", rxData);
    }
}