noderoute: Fix logic for URADVD warnings

This bug was intruduced in:
1bad4a7c noderoute: fix shellcheck warnings

Without this fix all client nodes will always report URADVD problems.
But server nodes never will. :-/

gluon-ffbsnext-nodeconfig/files/usr/sbin/noderoute.sh

@@ -34,7 +34,7 @@ while true; do
     fi
     sleep 10
 
-    if ! batctl gw | grep -q server; then
+    if batctl gw | grep -q server; then
         # sanity check: is uradvd running?
         if ! pidof uradvd > /dev/null; then
             $LOGGER ERROR: NO URADVD RUNNING.