media: v4l2-mem2mem: Fix outdated documentation

media: v4l2-mem2mem: Fix outdated documentation

Commit cbd9463da1b1 ("media: v4l2-mem2mem: Avoid calling .device_run in
v4l2_m2m_job_finish") deferred calls to .device_run() to a work queue to
avoid recursive calls when a job is finished right away from
.device_run(). It failed to update the v4l2_m2m_job_finish()
documentation that still states the function must not be called from
.device_run(). Fix it.

Fixes: cbd9463da1b1 ("media: v4l2-mem2mem: Avoid calling .device_run in v4l2_m2m_job_finish")
Cc: stable@vger.kernel.org
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>