[media] v4l: vsp1: Fix format-info documentation

Minor tweaks to document the swap register and make the documentation
match the struct ordering

Signed-off-by: Kieran Bingham <kieran@bingham.xyz>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>