recovery: add overlay interface for recovery mode

Pan display needs FB allocation from driver and
since it is removed from driver, switching to overlay
interfaces in recovery mode. Basically forking out
the overlay and pan_display path in separate files.

Change-Id: I60f13e54befaa6da77e6c4d23399835509b41333
recovery: Add support for split display

Configure LEFT and RIGHT mixer separately
to drive high resolution display.

Change-Id: I3a3e6bffe6373caa991d9847dae6f2f4d8d20c48
recovery: Fix compilation for non MSM target

Make mdp5 version variable scope valid for non-MSM target.

Change-Id: Ib02c7d8f79c6d29e8f14b58810f628c3a80d416d