Add an additional bit for the GPS signal level

The extra state indicating GPS is turned off.
 -00: poor signal level
 -01: good signal level
 -10: none (no signal)
This change is designed to work with cl/529249005 to fix the misleading
information in Battery Historian GPS signal quality UI bar

Test: Battery Historian UI
Bug: 259729405
Change-Id: I9db7035156c82c8cf0570b6349336aec1b253bce