jf: Add configuration for panel auto-brightness mode

 * JF's panel needs a 1 written to the sysfs node to enable proper
   CABC behavior when auto-brightness is enabled.
 * The driver actually supports a special mode 6, which is very
   aggressive but might be pleasing to some. We will add support for
   this in the device settings apps.

Change-Id: Ic4da86de1dc02bc5c7e9190f1e94e09f3b02a1e3