iio: imu: adis16475: correct copy paste mistake in comment block

The minimal advised lower rate for adis16475 compatible devices is
1900HZ and not 4000HZ. Set that right in the comments so that it does
not generate any confusion.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20230213153208.1027602-1-nuno.sa@analog.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>