staging:iio: Remove declaration for non existing function

The declaration for iio_buffer_deinit has been around for quite some time, but
the function itself has never been added. So remove the declaration.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/iio/buffer.h

@@ -91,8 +91,6 @@ struct iio_buffer {
  **/
 void iio_buffer_init(struct iio_buffer *buffer);
 
-void iio_buffer_deinit(struct iio_buffer *buffer);
-
 /**
  * __iio_update_buffer() - update common elements of buffers
  * @buffer:		buffer that is the event source