d2: Add configuration for panel auto-brightness mode

 * D2 needs the sysfs knob set to 1 to enable proper gamma
   configuration.

Change-Id: I2bbd66cf89a8234af884469884eaf34eb2488b7a
Merge "d2: Add configuration for panel auto-brightness mode" into cm-10.1
Merge remote-tracking branch 'upstream/cm-10.1' into HEAD

Change-Id: Ic4129523a6629054c3703e4599d8a9fccc7af008