Telephony: STK CC feature implementation

Add strings and constants required for stk cc feature.

Change-Id: Ic8e57ac2d39ca9187959c11e7e9e26e9fe6dc71d
Avoid collision with RIL constant 1138, used in some Samsung devices for RIL_UNSOL_TETHERED_MODE_STATE_CHANGED.
Needs http://review.cyanogenmod.org/#/c/61292/
Thanks to iptux on XDA for pointing out the change in constants between
CM-10.2 and CM-11.0.

Change-Id: I64011408f4cce9aeb1b56e325226f8e649eff2b6
Merge remote-tracking branch 'pac/pac-4.4' into pac-4.4