drm/msm: Split out helper to get comm/cmdline

Deduplicate this from fault_worker and recover_worker.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Link: https://lore.kernel.org/r/20220317165144.222101-3-robdclark@gmail.com


Signed-off-by: Rob Clark <robdclark@chromium.org>