drm/msm: Use labels for unwinding in the error path

This simplifies cleanup, to make sure nothing drops out in case of
error.

Changes in v3:
- None

Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
[seanpaul split out of dpu megapatch and renamed labels]
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>