media: v4l: subdev: Fix typo in documentation

Replace the incorrect reference to the v4l2_subdev_enable_stream()
function with the correct v4l2_subdev_enable_streams() spelling.

Fixes: d0749adb ("media: v4l2-subdev: Add subdev .(enable|disable)_streams() operations")
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/r/20240619225343.15873-1-laurent.pinchart@ideasonboard.com


Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>