Revert "drm/i915: start adding dp mst audio"

Right now MST audio is causing too many kernel panics to really keep
around in the kernel. On top of that, even after fixing said panics it's
still basically non-functional (at least on all the setups I've tested
it on). Revert until we have a proper solution for this.

This reverts commit 3d52ccf5.

Signed-off-by: Lyude <cpaul@redhat.com>
Fixes: 3d52ccf5 ("drm/i915: start adding dp mst audio")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462287692-28570-1-git-send-email-cpaul@redhat.com