drm/msm: fix potential NULL dereference in cleanup

The "msm_obj->node" list needs to be initialized earlier so that the
list_del() in msm_gem_free_object() doesn't experience a NULL pointer
dereference.

Fixes: 6ed0897c ("drm/msm: Fix debugfs deadlock")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20211013081133.GF6010@kili


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