Disallow data when QNS switched the preference

When the preference has switched to another transport, do
not allow data setup. This avoid the case that data service
keeps asking telephony to retry while QNS already switched
the preference to another transport.

Test: Manual
Fix: 182899920
Fix: 175399007
Change-Id: I1a0c86a978756d5b05851d939e011010f8f1afc2

telephony/java/android/telephony/AccessNetworkConstants.java

@@ -62,6 +62,7 @@ public final class AccessNetworkConstants {
         switch (transportType) {
             case TRANSPORT_TYPE_WWAN: return "WWAN";
             case TRANSPORT_TYPE_WLAN: return "WLAN";
+            case TRANSPORT_TYPE_INVALID: return "INVALID";
             default: return Integer.toString(transportType);
         }
     }