drm: rcar-du: lvds: Allow for even and odd pixels swap

DT properties dual-lvds-even-pixels and dual-lvds-odd-pixels
can be used to work out if the driver needs to swap even
and odd pixels around.

This patch makes use of the return value from function
drm_of_lvds_get_dual_link_pixel_order to determine if we
need to swap odd and even pixels around for things to work
properly.

The dual_link boolean field from struct rcar_lvds is not
sufficient to describe the type of LVDS link anymore, since
we now have information related to pixel order, therefore
rename it to link_type and repurpose its usage to fit the
new requirements.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>