kernel/power/powersuspend: LCD screen on/off hooks (Yank555.lu)

- add an alternative hook for screen on / off detection in the display
  pannel driver
- sleeps  ~0.1s sooner, wakes up ~1s later then autosleep
- clean up source formatting a bit (Paul Reioux)

Change-Id: Id04a51567889cf528dd776f92fcea18dbc8493f2
Signed-off-by: Paul Reioux <reioux@gmail.com>