iio: add kernel-doc for field @owner

When building kernel documentation sphinx emits the following warning

	warning: No description found for parameter 'owner'

Add description for struct member 'owner'.
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/iio/trigger.h

@@ -43,6 +43,7 @@ struct iio_trigger_ops {
 /**
  * struct iio_trigger - industrial I/O trigger device
  * @ops:		[DRIVER] operations structure
+ * @owner:		[INTERN] owner of this driver module
  * @id:			[INTERN] unique id number
  * @name:		[DRIVER] unique name
  * @dev:		[DRIVER] associated device (if relevant)