msm: kgsl: Add the A6XX preemption buffers to snapshot

Dump a block of the preemption buffers of every ringbuffer that is dumped
in the snapshot. This helps in debugging preemption issues. Also dump A5XX
preemption buffers with every ringbuffer that is dumped.

Change-Id: Ib56e2fc0ef926853b36d70f54f3403b8feb02994
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>
Signed-off-by: Mohammed Mirza Mandayappurath Manzoor <mmandaya@codeaurora.org>