Camera button support (1/2)

Add new bitmask for Camera button and "hasCamera" boolean.
For those devices that have dedicated Camera key
(like Sony ZL/ZR/Z1/...)

Change-Id: I1a6681664f9f3fd3f30221ba10b082cb5f8cafca
Merge remote-tracking branch 'cm/cm-10.2' into cm-10.2