The interface to configure the LIF in the VSP1 requires adapting the
function prototype for any changes. This makes extending the interface
difficult.

Change the function prototype to pass a structure which can be easily
extended.

This changes the means of disabling the pipeline, by now passing a NULL
configuration rather than passing either a 0 width or height.

[Fixed kerneldoc, made vsp1_du_setup_lif() cfg argument const]
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>