dgram: use simplified validator

The `dgram` lib module should use the simplified `validatePort()`
validator.

lib/dgram.js

@@ -369,7 +369,7 @@ Socket.prototype.bind = function(port_, address_ /* , callback */) {
 };
 
 Socket.prototype.connect = function(port, address, callback) {
-  port = validatePort(port, 'Port', { allowZero: false });
+  port = validatePort(port, 'Port', false);
   if (typeof address === 'function') {
     callback = address;
     address = '';