Initialize mPendingAutoBrightnessAdjustment to NaN.

It currently defaults to 0 which is a valid adjustment, so if you have
a pre-existing adjustment it will get reset at every reboot and look
like a user adjustment.

Also, go ahead and set the pending adjustment to NaN if we've seen it
before so we don't try to apply it again in the future.

Bug: 80119319
Test: manual
Change-Id: I206f6d631ec2977a2c1a44f91e0c6c6a09ccd7ec

services/core/java/com/android/server/display/DisplayPowerController.java

@@ -489,6 +489,7 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
         mTemporaryScreenBrightness = -1;
         mPendingScreenBrightnessSetting = -1;
         mTemporaryAutoBrightnessAdjustment = Float.NaN;
+        mPendingAutoBrightnessAdjustment = Float.NaN;
     }
 
     /**
@@ -1499,6 +1500,7 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
             return false;
         }
         if (mAutoBrightnessAdjustment == mPendingAutoBrightnessAdjustment) {
+            mPendingAutoBrightnessAdjustment = Float.NaN;
             return false;
         }
         mAutoBrightnessAdjustment = mPendingAutoBrightnessAdjustment;