gps: Added switching to GPS srs client mode

Change-Id: Ia9ae3f31388df5714aa95b5df65b960965baec5d
libgps: Calling JNI GPS callbacks in proper thread

Change-Id: I9f019810b3b5ed6fdae03f73ad7a1174bbde73c7
[GPS] Added SRS_GPS_STATE callbacks
Fixed gps state handling