DO NOT MERGE refactor wifi p2p's startDhcpServer function

Add getTetheredDhcpRanges() interface and call it before calling
mNwService.startTethering() to update dhcp ranges. This will allow p2p app
to run well concurrently with other tethering app(e.g. usb tethering).

Change-Id: I5e8ffeb5d2d396f48b897cd9396f133e25ecca57
Signed-off-by: Jianzheng Zhou <jianzheng.zhou@freescale.com>

services/java/com/android/server/ConnectivityService.java

@@ -3297,6 +3297,11 @@ public class ConnectivityService extends IConnectivityManager.Stub {
         return mTethering.getTetherableIfaces();
     }
 
+    public String[] getTetheredDhcpRanges() {
+        enforceConnectivityInternalPermission();
+        return mTethering.getTetheredDhcpRanges();
+    }
+
     public String[] getTetheredIfaces() {
         enforceTetherAccessPermission();
         return mTethering.getTetheredIfaces();