kgsl/drm: Remove use of deprecated memory barriers

Replace deprecated smp_mb__*_atomic_inc() memory
barrier API with smp_mb__*_atomic() API. This is
required to avoid build errors.

Change-Id: I5606e22177cef4b283f9d21a0432c09f59afbf2d
Signed-off-by: Deepak Kumar <dkumar@codeaurora.org>