drm/i915: Refresh that status of MST capable connectors in ->detect()

Once we've determined that the sink is MST capable we never end up
running through the full detect cycle again, despite getting HPDs.
Fix tht by ripping out the incorrect piece of code responsible.

This got broken when I moved the long HPD handling to the ->detect()
hook, but failed to remove the leftover code.

Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Cc: Rui Tiago Matos <tiagomatos@gmail.com>
Tested-by: Rui Tiago Matos <tiagomatos@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98323


Cc: Kirill A. Shutemov <kirill@shutemov.name>
Tested-by: Kirill A. Shutemov <kirill@shutemov.name>
References: https://bugs.freedesktop.org/show_bug.cgi?id=98306


Fixes: 10158116 ("drm/i915: Move long hpd handling into the hotplug work")
Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1477057478-29328-1-git-send-email-ville.syrjala@linux.intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
(cherry picked from commit 1aab956c)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>