media: v4l: async: Drop useless list move operation

v4l2_async_unbind_subdev_one(), which is called in the line
following the list_move() operation contains list_move_tail()
for the same entry and overrides anything list_move() did.
Thus it can be removed.

Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>