dt-bindings:iio:samsung, exynos-adc: drop missuse of io-channel-ranges

io-channel-ranges is a property for consumers of io-channels, not
providers.  Hence it is not relevant in this binding or the examples
given.

Recent changes to dt-schema result in this being reported as an error
as a dependency is enforced between this property and io-channels.

Reported-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201115192951.1073632-3-jic23@kernel.org