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>