[media] v4l: vsp1: pipe: Fix typo in comment

The vsp1_pipeline wq field is a wait queue, not a work queue. Fix the
comment accordingly.

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