iio: add field identifier for @use_count kernel-doc

Kernel-doc for @use_count does not currently have a field identifier.
All the rest of the fields do. @use_count is used internally and should
not be accessed directly by the driver so it should be marked as so.

Add [INTERN] identifier to @use_count field.
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

@@ -49,7 +49,7 @@ struct iio_trigger_ops {
  * @dev:		[DRIVER] associated device (if relevant)
  * @list:		[INTERN] used in maintenance of global trigger list
  * @alloc_list:		[DRIVER] used for driver specific trigger list
- * @use_count:		use count for the trigger
+ * @use_count:		[INTERN] use count for the trigger.
  * @subirq_chip:	[INTERN] associate 'virtual' irq chip.
  * @subirq_base:	[INTERN] base number for irqs provided by trigger.
  * @subirqs:		[INTERN] information about the 'child' irqs.