Add support for Socionext Synquacer SDHCI. This binding has been in use for
some time.

The interrupts were not documented. The driver only uses the first
interrupt, but the DT and example have 2 interrupts. The 2nd one is
unknown. "dma-coherent" was also not documented, but is used on Synquacer.
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/20230319173006.30455-1-robh@kernel.orgSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>