arm: mach-k3: am625: Provide a way to obtain boot device for non SPLs

Introduce get_boot_device() to obtain the booting device. Make it also
available for non SPL builds so u-boot can also know the device it is
booting from.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
5 files changed