Revert "Revert "Telephony: Add getLteOnGsmMode() method (1/2)""

This reverts commit a86d6de43c231b3dce02fd60edaf8cb7c8495913

Change-Id: If3d6bd9caf9231eff9444c1b1311f531157b32a6
Merge "Revert "Revert "Telephony: Add getLteOnGsmMode() method (1/2)""" into jellybean