client: Fix use of g_free

g_free shall only be used with pointer allocated with g_* functions.
diff --git a/client/advertising.c b/client/advertising.c
index 045133a..39f9946 100644
--- a/client/advertising.c
+++ b/client/advertising.c
@@ -733,7 +733,7 @@
 	ad.name = value;
 
 	if (!value) {
-		g_free(ad.local_name);
+		free(ad.local_name);
 		ad.local_name = NULL;
 	}