[media] v4l: vsp1: wpf: Add flipping support

Vertical flipping is available on both Gen2 and Gen3, while horizontal
flipping is only available on Gen3.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>