vty: Don't print error if removing auth data while none present

It's a bit confusing to the user if he wants to set AUD=none
and it's already none.  Avoid printing error messages in that case.

Change-Id: I5f32dd5d6e4939c738faf442c7e86671d18777f8
diff --git a/src/hlr_vty_subscr.c b/src/hlr_vty_subscr.c
index 5a300a7..7191a1c 100644
--- a/src/hlr_vty_subscr.c
+++ b/src/hlr_vty_subscr.c
@@ -334,7 +334,7 @@
 
 	rc = db_subscr_update_aud_by_id(g_hlr->dbc, subscr.id, &aud);
 
-	if (rc) {
+	if (rc && rc != -ENOENT) {
 		vty_out(vty, "%% Error: cannot disable 2G auth data for IMSI='%s'%s",
 			subscr.imsi, VTY_NEWLINE);
 		return CMD_WARNING;
@@ -405,7 +405,7 @@
 
 	rc = db_subscr_update_aud_by_id(g_hlr->dbc, subscr.id, &aud);
 
-	if (rc) {
+	if (rc && rc != -ENOENT) {
 		vty_out(vty, "%% Error: cannot disable 3G auth data for IMSI='%s'%s",
 			subscr.imsi, VTY_NEWLINE);
 		return CMD_WARNING;