msm: kgsl: Improve GPU snapshot design

If GPU recovers from fault, KGSL shall continue doing GPU snapshot
in case GPU/GMU faults again. If GPU fault cannot be recovered,
stop taking new GPU snapshot. Keep the snapshot of last
unrecoverable snapshot for post-mortem debugging.

Change-Id: I988a7ee8f8b01dbf57bc4751708c5cf33bea835e
Signed-off-by: George Shen <sqiao@codeaurora.org>