msm: kgsl: Enable preemption for A615 gpu

Enable the preemption feature for A615 gpu. This feature helps in
improving Quality of Service.

Change-Id: I874da734a5734af8331d9cd888d106a6cd71304d
Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>
Signed-off-by: Urvashi Agrawal <urvaagra@codeaurora.org>