Otherwise the MST resume paths can hit DPMS paths
which hit state checker paths, which hit WARN_ON,
because the state checker is inconsistent with the
hw.
This fixes a bunch of WARN_ON's on resume after
undocking.
Signed-off-by: Dave Airlie <airlied@redhat.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula <jani.nikula@intel.com>