Telephony: prevent NPE

Change-Id: Ia7a08334a901ef67353d5816d0822d0cb2d57daf
SamsungExynos3RIL: rebase to latest RIL

Change-Id: Ibb15014055b1648fe073f4bf6b1ff673271caab4
Telephony: Query SignalStrength when there is a RAT change.

In CdmaLte phone when RAT switch happens, telephony receiving
new signal info before updating to new RAT and because of that
the received signal info is ignored and empty bars updated
on UI. To avoid that query signal strength info when there
is a change in PS RAT happens.
CRs-Fixed: 464438

Change-Id: If494b9380f47bd82fe4f5dec03f9538c7ab76b49