drm/i915: Make DP-MST connector info work

Commit 9a148a96 ("drm/i915/debugfs: add dp mst info") adds support
for DP-MST to intel_connector_info, but forgot to remove the early
return for DP-MST.

Remove it, and print out MST connectors directly.

Fixes: 9a148a96 ("drm/i915/debugfs: add dp mst info")
Cc: <stable@vger.kernel.org> # v4.11+
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Libin Yang <libin.yang@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170626083349.24389-1-maarten.lankhorst@linux.intel.com


Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
(cherry picked from commit 77d1f615)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>