drm/i915: make SDVO TV-out work for multifunction devices

commit 09ede5414f0215461c933032630bf9c3a61a8ba3 upstream.

We need to track this correctly. While at it shovel the boolean
to track whether the sdvo is in tv mode or not into pipe_config.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=36997


Tested-by: Pierre Assal <pierre.assal@verint.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=63609


Tested-by: cancan,feng <cancan.feng@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>