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: Id105f0329007c4f7ff008d4f2f34314f2e16fba7
Signed-off-by: Steve Cohen <cohens@codeaurora.org>
Signed-off-by: Abhijith Desai <desaia@codeaurora.org>