luci-base: validate name in firewall zone selector widget

When creating a new zone through the firewall zone selector widget,
validate the given name before creating new items.

Depends on commit 0b6ae96f2 ("luci-base: cbi.js: recognize invalid
input in dropdown create field").

Fixes: #2211
Signed-off-by: Jo-Philipp Wich <jo@mein.io>

modules/luci-base/luasrc/view/cbi/firewall_zonelist.htm

@@ -98,7 +98,7 @@
 			<span class="zonebadge">
 				<em><%:create%>:</em>
 				<input type="password" style="display:none" />
-				<input class="create-item-input" type="text" />
+				<input class="create-item-input" type="text" data-type="and(uciname,maxlength(11))" data-optional="true" />
 			</span>
 		</li>
 		<% end %>