gnss@1.0-service: drop inet group, add gps group

Both system and gps groups might be relevant to the implementation of a
GNSS HAL.

b/36651420 [QCOM Treble] marlin/sailfish location daemon uses Binder
b/36085168 STOPSHIP - HAL (GNSS) cannot have internet access
b/35757613 STOPSHIP:  O GNSS TTFF - Regressed to Cold Start (XTRA
	   broken) (revert SELinux Change)

Test: marlin

Change-Id: I8aa5b18ef094b8540e7838174154f060a0c3fa9a
Merged-In: I8aa5b18ef094b8540e7838174154f060a0c3fa9a
Signed-off-by: Iliyan Malchev <malchev@google.com>