LGEQualcommRIL: Clean up processUnsolicited

At David Ferguson <ferguson.david@gmail.com>'s suggestion, remove
the full overload of processUnsolicited and have it just work with
the requests unknown by the RIL superclass. Pass everything else
upwards, unmodified.

Change-Id: Ie019fbaa3d5010bf7adc5528f3d523a77efb146f