Fix locking in AnyMotionDetector.

1. Make sure we appropriately lock around mState when accessing and
   changing it.
2. Annotate lock requirements around variables
3. Don't call the callback with the lock held. This could have resulted
   in a deadlock, though I have no evidence that one did occur.

Bug: 199191752
Test: atest DeviceIdleTest
Test: atest FrameworksMockingServicesTests:DeviceIdleControllerTest
Change-Id: I689145822462202afb2d4ba24ffd9e73cc1917ee