drm/i915/tv: fix gen4 composite s-video tv-out

This is *not* bisected, but the likely regression is

commit c3561438
Author: Zhao Yakui <yakui.zhao@intel.com>
Date:   Tue Nov 24 09:48:48 2009 +0800

    drm/i915: Don't set up the TV port if it isn't in the BIOS table.

The commit does not check for all TV device types that might be present
in the VBT, disabling TV out for the missing ones. Add composite
S-video.

Reported-and-tested-by: Matthew Khouzam <matthew.khouzam@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73362


Cc: stable@vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>