drm/i915/tv: Remember the detected TV type

During detect() we would probe the connection bits to determine if
there was a TV attached, and what video input type (Component, S-Video,
Composite, etc) to use. However, we promptly discarded this vital bit of
information and never propagated it to where it was used to determine
the correct modes and setup the control registers. Fix it!

This fixes a regression from 7b334fcb.

Reported-and-tested-by: Mathew McKernan <matmckernan@rauland.com.au>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35977


Signed-off-by: Mathew McKernan <matmckernan@rauland.com.au>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Acked-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Keith Packard <keithp@keithp.com>