Rename *Iface* APIs to *Interface*

Address API review feedback, other APIs have been refering to
these as "interface" instead of "iface" so migrate the APIs named
*Iface* to *Interface*.

Bug: 183972554
Test: atest android.net.UnderlyingNetworkInfoTest
Change-Id: I38b476e762fb57fa88c4a789092d0af6f5330d80

services/core/java/com/android/server/net/NetworkStatsFactory.java

@@ -382,8 +382,8 @@ public class NetworkStatsFactory {
 
         // Migrate data usage over a VPN to the TUN network.
         for (UnderlyingNetworkInfo info : vpnArray) {
-            delta.migrateTun(info.getOwnerUid(), info.getIface(),
-                    info.getUnderlyingIfaces());
+            delta.migrateTun(info.getOwnerUid(), info.getInterface(),
+                    info.getUnderlyingInterfaces());
             // Filter out debug entries as that may lead to over counting.
             delta.filterDebugEntries();
         }