msm: kgsl: Add genlock to KGSL DRM driver

This change is to enable frame buffers lock between multiple processes
through genlock.
Genlock is a in-kernel API and optional userspace interface for a generic
cross-process locking mechanism.

Change-Id: If07f024092caee4a257cd70d79799f4231a2cf46
Signed-off-by: Alex Wong <waiw@codeaurora.org>