efi_loader: efi_gop: use correct types for parameters

Use efi_uintn_t instead of unsigned long.

EFI_GRAPHICS_OUTPUT_BLT_OPERATION is an enum. If we don't
define an enum we have to pass it as u32.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>