drm: msm: a6xx: fix debug bus register configuration

Fix the cx debugbus related register configuration, to collect accurate
bus data during gpu snapshot. This helps with complete snapshot dump
and also complete proper GPU recovery.

Fixes: 1707add8 ("drm/msm/a6xx: Add a6xx gpu state")
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/339165