drm/i915/lvds: Always return connected in the absence of better information

The LVDS connector should default to connected. We tried our best to
verify the claims of the BIOS that the hardware exists during init(),
and then during detect() we then try to verify that the panel is open.
In the event of an unsuccessful query, we should then always report
that the LVDS panel is connected. This was only the case for gen2/3,
later generations leaked the return value from the panel probe instead.

Reported-and-tested-by: Alessandro Suardi <alessandro.suardi@gmail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>