Update route property reference.

In a separate CL, route.description was renamed to route.title.

Review URL: https://codereview.chromium.org/1111073002

Cr-Commit-Position: refs/heads/master@{#327420}

chrome/browser/resources/media_router/elements/media_router_sink/media_router_sink.html

@@ -7,7 +7,7 @@
     <div class="device cast-device"></div>
     <span>{{sink.name}}</span>
     <template if="{{route}}">
-      <div class="route">{{route.description}}</div>
+      <div class="route">{{route.title}}</div>
     </template>
   </div>
 </template>