imx8: add boot device detection

Add get_boot_device to detect boot device.
Add print_bootinfo to print the boot device info.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
2 files changed