dt-bindings: iio: drop unneeded quotes

Cleanup by removing unneeded quotes from refs and redundant blank lines.
No functional impact except adjusting to preferred coding style.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Dmitry Rokosov <ddrokosov@sberdevices.ru> # memsensing
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com> # sama5d2-adc
Reviewed-by: Puranjay Mohan <puranjay12@gmail.com> # tmp117
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com> # ad7292
Link: https://lore.kernel.org/r/20230124081037.31013-1-krzysztof.kozlowski@linaro.org


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