uboot-imx

arm: K3: am654: Add support for getting boot mode

Read the boot mode register to find the boot mode. Only use eMMC boot0
mode when the mode is eMMC boot (called BOOT_DEVICE_MMC1 currently due
to current conflating of boot mode and boot device), and not iff the
boot device is MMC port 0.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>