media: rzv2h-ivc: Replace workqueue with direct function call

media: rzv2h-ivc: Replace workqueue with direct function call

Scheduling of work items with an async workqueue opens the door to
potential races between multiple instances of a work item.

While the frame transfer function is now protected against races, using
a workqueue doesn't provide much benefit considering the limited cost of
creating a job transfer.

Replace the usage of the work queue with direct function calls.

Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>