efi_loader: use %pUs for printing GUIDs

For printing GUIDs with macro EFI_ENTRY use %pUs instead of %pUl to provide
readable debug output.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

lib/efi_loader/efi_image_loader.c

@@ -676,7 +676,7 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
 				continue;
 			}
 			if (guidcmp(auth, &efi_guid_cert_type_pkcs7)) {
-				EFI_PRINT("Certificate type not supported: %pUl\n",
+				EFI_PRINT("Certificate type not supported: %pUs\n",
 					  auth);
 				continue;
 			}