Framework: Fix GSM signal strength

Certain OEM gsm ril libs send back a bogus value for LTE signal
that causes SignalStrength.java to default to LTE and report
incorrect signal values.
Use prop value ro.telephony.ril.v3=signalstrength to get proper
GSM signal reading on certain devices.

Signed-off-by: dhacker29 <davidhackerdvm@gmail.com>

Change-Id: I86279dcbc350fe718d89070acc12178de3c600c2

Conflicts:

	telephony/java/android/telephony/SignalStrength.java
Revert "Framework: Fix GSM signal strength"

This reverts commit 47a3aa7bb1af053c5450807d2ed60f7c4479c4c1.