dt-bindings: mmc: renesas,sdhi: convert to YAML

Convert Renesas SDHI SD/MMC controller document to YAML.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1594363883-22154-1-git-send-email-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>