drm/msm/sde: ensure all local atomic states get freed

Make sure that any time an atomic state is allocated
that the reference to that object is put back when
it's no longer needed. This will avoid leaking memory.

Change-Id: If95209573415b4c5d9c8b0d5c111865390dbfda8
Signed-off-by: Steve Cohen <cohens@codeaurora.org>