dt-binding:iio:adc:ti,ads124s08: txt to yaml format conversion.

Simple binding so straight forward format conversion.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Link: https://lore.kernel.org/r/20201031184854.745828-38-jic23@kernel.org