media: intel/ipu6: Change deprecated lock comment

pre_streamon_queued is no longer used. The lock now is protecting active
and incoming lists.

Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>