Convert H8/300 bus controller bindings to DT schema format using
json-schema.

The conversion also extends the bindings to match what is really used in
existing devicetree sources (the original file mentions only
"renesas,h8300-bsc" but "renesas,h8300h-bsc" and "renesas,h8s-bsc" are
used with it).
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210818202953.16862-1-krzysztof.kozlowski@canonical.comSigned-off-by: Rob Herring <robh@kernel.org>