gprs/gprs_gmm: implement T3314. Timeout to reset MM state READY->STANDBY

When a MS MM state is READY its exact location is known (PCU).
On Gb, T3314 (aka TS 23.060 "READY timer") sets the MM state from
READY to STANDBY, where only the RA is known.

Introduce a second set of timer variables, because state timer
can run while another packet state timer is timing out.

Related: OS#1941
Change-Id: I4ce23ebe50d141076c20c9c56990b7103cd25e55
1 file changed