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

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: 1015811609c0 ("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 1aab956c7b8872fb6976328316bfad62c6e67cf8)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>