iio: fix SPHINX kernel-docs build warning

When building kernel documentation sphinx emits the following warnings

No description found for parameter 'iio_dev'
Excess function parameter 'indio_dev' description in 'iio_device_register'

These warnings are caused by a macro with a different argument identifier to the
one listed in the kernel-docs.

Change macro argument to be the same as the docs.
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/iio.h

@@ -606,8 +606,8 @@ const struct iio_chan_spec
  * iio_device_register() - register a device with the IIO subsystem
  * @indio_dev:		Device structure filled by the device driver
  **/
-#define iio_device_register(iio_dev) \
-	__iio_device_register((iio_dev), THIS_MODULE)
+#define iio_device_register(indio_dev) \
+	__iio_device_register((indio_dev), THIS_MODULE)
 int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod);
 void iio_device_unregister(struct iio_dev *indio_dev);
 /**