log: only include LOC and method name in debug logs if running with --debug

If the modem is started with --log-level=DEBUG, they will not be shown.

src/main.c

@@ -115,6 +115,7 @@ main (int argc, char *argv[])
                        mm_context_get_log_file (),
                        mm_context_get_timestamps (),
                        mm_context_get_relative_timestamps (),
+                       mm_context_get_debug (),
                        &err)) {
         g_warning ("Failed to set up logging: %s", err->message);
         g_error_free (err);