eMMC as boot media support in RZ-FIVE

Hello.

Currently for RZ-FIVE in v3.0.3 BSP, only QSPI boot is supported. When we try to boot from eMMC below error is observed:

U-Boot SPL 2021.10-g711334a179-dirty (Apr 18 2023 - 11:58:08 +0530)
SPL: Unsupported Boot Device!
SPL: failed to boot from all boot devices
### ERROR ### Please RESET the board ###

But we want eMMC as boot media support.

Kindly share the SW changes to support eMMC as boot media.

Regards.