efi_loader: correct size for tpl level

The UEFI standard defines the type for the tpl level as EFI_TPL
alias UINTN.

UINTN is an integer is defined as an unsigned integer of native
width. So we can use size_t for the definition.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 3d18bfb..b922720 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -77,7 +77,7 @@
  */
 struct efi_event {
 	u32 type;
-	unsigned long notify_tpl;
+	UINTN notify_tpl;
 	void (EFIAPI *notify_function)(struct efi_event *event, void *context);
 	void *notify_context;
 	u64 trigger_next;