Makefile: Don't "clean" iptables

Makefile

@@ -76,7 +76,6 @@ update-glide:
 
 clean:
 	rm -f dist/flanneld*
-	rm -f dist/iptables*
 	rm -f dist/libpthread*
 	rm -f dist/*.aci
 	rm -f dist/*.docker
@@ -231,4 +230,4 @@ run-etcd: stop-etcd
 	--listen-client-urls "http://0.0.0.0:2379,http://0.0.0.0:4001"
 
 stop-etcd:
-	@-docker rm -f flannel-etcd
+	@-docker rm -f flannel-etcd