telephony: set PROPERTY_DATA_NETWORK to data technology

The GSM SS is inaccurately setting the property to voice technology
instead of data technology (CDMA's SS is correct.)

Change-Id: I35a0a789bc06159f65325946e43f166f531bb1cc
Telephony: prevent NPE

Change-Id: Ia7a08334a901ef67353d5816d0822d0cb2d57daf
Merge "Telephony: prevent NPE" into cm-10.2
Merge remote-tracking branch 'upstream/cm-10.2' into cm-10.2