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

Same functionality as the existing getLteOnCdmaMode, but for GSM
LTE devices.
Enable with the telephony.lteOnGsmDevice system property

From CM 10.0: Ibfb47ca608e51393b99d3308e0a6c66050b3f32e
- Moved getLteOnGsmModeStatic() to TelephonyManager.
Samsung STK support

Change-Id: I08d169bc466df290fca838b09f6b0fbea2ac82a8

Conflicts:
	core/res/res/values/config.xml