Resume GNSS measurement reporting when location setting is back on.

The mGnssMeasurementsProvider.onGpsEnabledChanged() and
mGnssNavigationMessageProvider.onGpsEnabledChanged() methods called
from handleEnable() and handleDisable() methods expect the mEnabled
flag to be already updated before they are called. They check mEnabled
to reregister listeners with the GNSS HAL when the master location
setting is turned back on.

Fixes: 126715741
Test: Tested with a Pixel device before and after this fix.
      Verified that measurements reporting resumes when the
      master location settings is turned back on.

Change-Id: Ia1f5edaf3e65fffec9ddf108fd726dd03376047e