[U-Boot] efi_loader: gop: fixes for CONFIG_DM_VIDEO without CONFIG_LCD

[Alexander Graf]

> Make EFI GOP support work with DM_VIDEO but without legacy LCD.
> 
> Signed-off-by: Rob Clark <robdclark at gmail.com>
> Cc: Alexander Graf <agraf at suse.de>

Thanks, applied to efi-next

Alex