dt-bindings: mmc: Convert Broadcom STB SDHCI binding to YAML

Convert the Broadcom STB SDHCI controller Device Tree binding to YAML.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20211208003727.3596577-2-f.fainelli@gmail.com


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