msm: kgsl: Don't use trace bus to dump A4XX debug bus data

If the GPU is running in an infinite loop then it is not
really hung but we still need to dump the snapshot in such cases
to understand the infinite loop. In such cases using the trace
bus to dump the A4XX debug bus data can lead to ASYNC errors
followed by system hang. Avoid this by not using trace bus to
dump debug bus data.

CRs-fixed: 598156
Change-Id: I7dada78eba1c64917f34eb64fa43e5faca94197d
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>