[media] v4l: vsp1: Rename video pipeline functions to use vsp1_video prefix

Those functions are specific to video nodes, rename them for
consistency.

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