dnsmasq: drop --interface and --except-interface options when the interface cannot be found

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/network/services/dnsmasq/files/dnsmasq.init

@@ -119,12 +119,12 @@ append_ipset() {
 }
 
 append_interface() {
-	network_get_device ifname "$1"
+	network_get_device ifname "$1" || return
 	xappend "--interface=$ifname"
 }
 
 append_notinterface() {
-	network_get_device ifname "$1"
+	network_get_device ifname "$1" || return
 	xappend "--except-interface=$ifname"
 }