Animate backlight quickly when display state request to change or power mode changed

* mAppliedDimming should be false when power request policy is not dim.
  * mAppliedLowPower should be false when low power mode is disabled.
  * Backlight brightness changes quickly.

Change-Id: I44bf9c216554f8dce5abd0520f198824df5e8dcf
Signed-off-by: mochangming <mochangming@xiaomi.com>

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

@@ -673,6 +673,9 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
                 slowChange = false;
             }
             mAppliedDimming = true;
+        } else if (mAppliedDimming) {
+            slowChange = false;
+            mAppliedDimming = false;
         }
 
         // If low power mode is enabled, cut the brightness level by half
@@ -685,6 +688,9 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
                 slowChange = false;
             }
             mAppliedLowPower = true;
+        } else if (mAppliedLowPower) {
+            slowChange = false;
+            mAppliedLowPower = false;
         }
 
         // Animate the screen brightness when the screen is on or dozing.