[media] omap3isp: queue: Don't build scatterlist for kernel buffer

The scatterlist is not needed for those buffers, don't build it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>