Auto adjust screen brightness when display state on while docked

Enable the auto screen brightness for display on when docked.
DOZE_AOD_DOCKED has STATE_ON display state in cases when
we don't need to worry about registering for the brightness sensor when
the display is on (ie: getSelectivelyRegisterProxSensor=false OR
brightness sensor doesn't use prox)

With this change, devices with getSelectivelyRegisterProxSensor=true
and brightnessSensorUsesProx=true will still not register for the
brightness sensor when the display state is on.

Bug: 194151347
Test: atest DozeScreenBrightnessTest
Test: manually verify under DOZE_AOD_DOCKED on devices with and w/o
under display prox sensors / brightness sensors that use prox

Change-Id: I04f88e7639a9cb0510a985d220da91fd1fb54313