efi_loader: wrong type in wait_for_event

The UEFI spec defines parameter index of WaitForEvent as UINTN*.
So we should use size_t here.

I deliberately do not use UINTN because I hold a following patch
that will eliminate UINTN because uppercase types to not match
the U-Boot coding style.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_api.h b/include/efi_api.h
index aa4306a..c44dc9d 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -71,7 +71,7 @@
 					 enum efi_timer_delay type,
 					 uint64_t trigger_time);
 	efi_status_t (EFIAPI *wait_for_event)(unsigned long number_of_events,
-			struct efi_event **event, unsigned long *index);
+			struct efi_event **event, size_t *index);
 	efi_status_t (EFIAPI *signal_event)(struct efi_event *event);
 	efi_status_t (EFIAPI *close_event)(struct efi_event *event);
 	efi_status_t (EFIAPI *check_event)(struct efi_event *event);