telephony: Consolidate Qualcomm RIL implementations

The RIL code for qualcomm devices was getting a bit messy (and
with a fair amount of duplicate code), so move all common code
to a new shared class, and keep only the minimum necessary
method overrides in the device-specific implementations

Change-Id: I50bf1f4efa30e637c825d9c5bf40ba3f2f130924