drm/msm/a3xx: remove TPL1 regs from snapshot

These regs are write-only, and the hw throws a hissy-fit (ie. reboots)
when we try to read them for GPU state snapshot, in response to a GPU
hang.  It is rather impolite when GPU recovery triggers an insta-
reboot, so lets remove the TPL1 registers from the snapshot.

Fixes: 7198e6b0 drm/msm: add a3xx gpu support
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>