gluon-radvd: fix init script

Fixes #862

package/gluon-radvd/files/etc/init.d/gluon-radvd

@@ -6,7 +6,7 @@ START=50
 start_service() {
   [ -x /lib/gluon/radvd/arguments ] && {
     procd_open_instance
-    procd_param command /usr/sbin/uradvd $(/lib/gluon/radvd/arguments)
+    procd_set_param command /usr/sbin/uradvd $(/lib/gluon/radvd/arguments)
     procd_set_param respawn ${respawn_threshold:-3600} ${respawn_timeout:-5} ${respawn_retry:-5}
     procd_set_param netdev br-client
     procd_set_param stderr 1