[Feature] TDIS-4463, Power module update

Update list
- TurnScreenOff() don't affect the value of brightness
- TurnScreenOn() will affect the value of brightness while
  brightness don't match the state has been requested
- request()/release() don't affect the value of brightness
- Accept multiple request(), rule will follow highest priority
  (BRIGHT > NORMAL > DIM)
- NORMAL state refers to the default screen brightness that
  a user has configured for the device
Merge pull request #180 from zivchang/next

[Feature] TDIS-4463, Power module update