drm/i915: Don't use the HDMI port color range bit on Valleyview

VLV docs still list the the color range selection bit for the HDMI
ports, but for DP ports it has been repurposed.

I have no idea whether the HDMI color range selection bit still works
on VLV, but since we now have to use the PIPECONF color range bit for
DP, we might as well do the same for HDMI.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>