Distro boot support gives flexibility to run distro RFS like Ubuntu
being deployed from SD card or SATA drive. If it fails to detect
external storage, fall back to qspi/sd boot.
Enable this by default in RDB's defconfig by selecting
CONFIG_DISTRO_DEFAULTS
Signed-off-by: Ashish Kumar <Ashish.Kumar@nxp.com>
Signed-off-by: Zhang Ying <zhangying@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>