vnc-tls: Clean up dead store in vnc_set_x509_credential()

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/ui/vnc-tls.c b/ui/vnc-tls.c
index 6392326..0f59f9b 100644
--- a/ui/vnc-tls.c
+++ b/ui/vnc-tls.c
@@ -444,8 +444,6 @@
     struct stat sb;
 
     g_free(*cred);
-    *cred = NULL;
-
     *cred = g_malloc(strlen(certdir) + strlen(filename) + 2);
 
     strcpy(*cred, certdir);