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>
1 file changed