dt-bindings: iio: adc: Document Renesas RZ/V2L ADC

Document renesas RZ/V2L ADC bindings. RZ/V2L ADC is identical to RZ/G2L
with same number of channels.

While at it remove RZ/G2LC SoC from binding documentation as it does not
support ADC.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220423131654.131390-1-biju.das.jz@bp.renesas.com


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