PROCESSOR-SDK-AM69A: How to read and write MAC values?

Part Number: PROCESSOR-SDK-AM69A

Tool/software:

I want to write a MAC value and be able to read it after powering on.
During the u-boot phase, I executed the following instructions:
i2c mw 0x51 0 0xab 1
i2c mw 0x51 1 0x55 1
i2c mw 0x51 2 0x33 1
i2c mw 0x51 3 0xee 1
i2c mw 0x51 4 0x01 1
...
i2c mw 0x51 51 0xaa 1
i2c mw 0x51 52 0xbb 1
i2c mw 0x51 53 0xcc 1
i2c mw 0x51 54 0xdd 1
i2c mw 0x51 55 0xee 1
i2c mw 0x51 56 0xff 1
After entering rootfs, the following results were obtained
 
I found that the MAC value did not change, as shown below:
 
How can I modify the MAC value?