camera: Add support for sending raw commands

 * Certain camera drivers need magic commands to select special modes
   such as ZSL or HDR. Add support for sending raw commands from
   applications.

Change-Id: I512a765c7a67ffd2877e465cf6493ffc2b3b54ac
power: Add panel auto-brightness configuration

 * Some panel hardware requires that we twiddle some knobs in sysfs to
   enable proper display calibration (gamma, etc) when auto-brightness
   is enabled. Add a configuration value to handle this.

Change-Id: I3c793c3520fc6f9a18d5a3abf1fe0df803c5e580