dt-bindings: adis16475: remove property

`adi,scaled-output-hz` is no longer used by the driver.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20210218114039.216091-4-nuno.sa@analog.com


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