efi_loader: definition of GetNextVariableName()

'vendor' is both an input and an output parameter. So it cannot be
constant.

Fixes: 0bda81bfdc5c ("efi_loader: use const efi_guid_t * for variable services")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/include/efi_api.h b/include/efi_api.h
index 4713da2..1c40ffc 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -272,7 +272,7 @@
 					    efi_uintn_t *data_size, void *data);
 	efi_status_t (EFIAPI *get_next_variable_name)(
 			efi_uintn_t *variable_name_size,
-			u16 *variable_name, const efi_guid_t *vendor);
+			u16 *variable_name, efi_guid_t *vendor);
 	efi_status_t (EFIAPI *set_variable)(u16 *variable_name,
 					    const efi_guid_t *vendor,
 					    u32 attributes,