iio: correct documentation for IIO_CONST_ATTR_SAMP_FREQ_AVAIL, match name of #define

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/iio/sysfs.h

@@ -97,7 +97,7 @@ struct iio_const_attr {
 #define IIO_DEV_ATTR_SAMP_FREQ_AVAIL(_show)				\
 	IIO_DEVICE_ATTR(sampling_frequency_available, S_IRUGO, _show, NULL, 0)
 /**
- * IIO_CONST_ATTR_AVAIL_SAMP_FREQ - list available sampling frequencies
+ * IIO_CONST_ATTR_SAMP_FREQ_AVAIL - list available sampling frequencies
  * @_string: frequency string for the attribute
  *
  * Constant version