video: sunxi: de2: Reserve the fb region in the EFI memory map

If compile with support for the efi loader we need to mark the pages
allocated for the framebuffer as reserved so the kernel won't attempt
to use them for other uses.

Signed-off-by: Emmanuel Vadot <manu@freebsd.org>
Acked-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>