Revert "drm/i915: Track active streams also for DP SST"

Revert "drm/i915: Track active streams also for DP SST"

This reverts commit f64425a82bdb5c3d7e09ba765716da88a9b00eec.

active_streams will get totally out of whack with SST unless we
sync up with the hw state at readout, obviously! We don't yet
do that, so now the WARNs fire all the time. Let's revert :(

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470413142-26402-1-git-send-email-ville.syrjala@linux.intel.com
References: https://bugs.freedesktop.org/show_bug.cgi?id=95472#c14
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>