media: v4l: vsp1: Remove unused field from vsp1_drm_pipeline structure

The vsp1_drm_pipeline enabled field is set but never used. Remove it.

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