AM625: Change saveenv mmc location

Hello,

I have gotten saveenv working on the SK-AM62-LP, but for the customer board they don't have an EMMC populated as mmc 0. I'm seeing that when I run saveenv on the LPSK it's saving the environment to mmc0:

## Resetting to default environment
=> setenv mmcdev 1;
=> saveenv
Saving Environment to MMC... Writing to MMC(0)... OK
=> reset

I see on previous sdk's we had an option to set the saveenv location through a u-boot config, but looking through the am62x_lpsk_a53_defconfig I don't see a similar setting where this is configured. How would I get the saveenv command to write to the mmc1 instead of to mmc0?

Munan