luci-base: network.js: expose prefixToMask() and maskToPrefix()

Expose the prefixToMask() and maskToPrefix() helper functions for use by
other modules, e.g. the datatype validator.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

modules/luci-base/htdocs/luci-static/resources/network.js

@@ -594,6 +594,9 @@ function deviceSort(a, b) {
 var Network, Protocol, Device, WifiDevice, WifiNetwork;
 
 Network = L.Class.extend({
+	prefixToMask: prefixToMask,
+	maskToPrefix: maskToPrefix,
+
 	flushCache: function() {
 		return Promise.resolve(_state).then(function() {
 			_flush = true;