drm/i915: Parametrize PANEL_PORT_SELECT_VLV

Passing the port as a parameter to PANEL_PORT_SELECT_VLV results in
neater code. Sadly the PCH port select bits aren't suitable for the
same treatment and the resulting macro would be much uglier, so
leave those defines as is.

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>