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

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.

Signed-off-by: Evan Anderson <evan1124@gmail.com>

Conflicts:
	src/java/com/android/internal/telephony/BaseCommands.java

Change-Id: I5c44c4b5f340312e69d4967417c686aea62635e2