Enforce mSettingsLock for WificondScannerImpl

This fixes a few places where mSettingsLock block is missing.
This also change the lock to static because there should only
be one WificondScannerImpl, static methods should be able to
access the lock.

Bug: 67059698
Test: compile, unit tests
Test: manually test that wifi scanner works
Change-Id: I57ecc288415450bae6f020e8566c5ebf2873e516
1 file changed