There is no reason to use OF_BOARD for MBV because reduced DT is used by
SPL and full DT is passed via u-boot.img or u-boot.itb. There is no reason
to pick up DTB from certain address.
Signed-off-by: Michal Simek <michal.simek@amd.com> Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>