Add icon mapping for NETWORK_TYPE_IWLAN

According to TelephonyManager#getNetworkClass, it seems to be a form
of 4g, so give it those icons.

Bug: 21338555
Change-Id: I00629572950191f30fd274367e95c3117990f671
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/policy/MobileSignalController.java b/packages/SystemUI/src/com/android/systemui/statusbar/policy/MobileSignalController.java
index 0aa0b4a..b21767b 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/policy/MobileSignalController.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/policy/MobileSignalController.java
@@ -191,6 +191,7 @@
         } else {
             mNetworkToIconLookup.put(TelephonyManager.NETWORK_TYPE_LTE, TelephonyIcons.LTE);
         }
+        mNetworkToIconLookup.put(TelephonyManager.NETWORK_TYPE_IWLAN, TelephonyIcons.FOUR_G);
     }
 
     @Override