ui/vnc: Fix use of free() instead of g_free()

Please note that mechlist still uses malloc / strdup / free.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/ui/vnc-tls.c b/ui/vnc-tls.c
index ffbd172..3aaa939 100644
--- a/ui/vnc-tls.c
+++ b/ui/vnc-tls.c
@@ -413,7 +413,7 @@
         vs->tls.session = NULL;
     }
     vs->tls.wiremode = VNC_WIREMODE_CLEAR;
-    free(vs->tls.dname);
+    g_free(vs->tls.dname);
 }