drm/msm: Remove abuse of drm_exec internals

drm/msm: Remove abuse of drm_exec internals

The code was reading drm_exec internal state to determine whether
the drm_exec structure had been initialized or not, and therefore
needed cleaning up, relying on undocumented behaviour.

Instead add a bool to struct msm_gem_submit to indicate whether
drm_exec cleaning up is needed.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Rob Clark <rob.clark@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/715502/
Message-ID: <20260331092023.81616-3-thomas.hellstrom@linux.intel.com>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>