am 4984e73d: Manage button and keyboard backlights with light sensor in both manual and automatic mode.

Merge commit '4984e73dc5fc3df757e4ac8dd333b88151deb3ea' into eclair-mr2

* commit '4984e73dc5fc3df757e4ac8dd333b88151deb3ea':
  Manage button and keyboard backlights with light sensor in both manual and automatic mode.