efi_loader: workaround for grub lsefi bug

Patch has also been sent to fix grub to not ignore the error returned
and treat protocol_buffer_count as valid.  But that that might take a
while to trickle into distro's, so this workaround might be useful.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

lib/efi_loader/efi_boottime.c

@@ -866,6 +866,7 @@ static efi_status_t EFIAPI efi_protocols_per_handle(void *handle,
 {
 	EFI_ENTRY("%p, %p, %p", handle, protocol_buffer,
 		  protocol_buffer_count);
+	*protocol_buffer_count = 0;
 	return EFI_EXIT(EFI_OUT_OF_RESOURCES);
 }