dt-bindings: arm: hisilicon: convert hisilicon,pctrl bindings to json-schema

Convert the Hisilicon peripheral misc control register binding to DT
schema format using json-schema.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20200929141454.2312-13-thunder.leizhen@huawei.com
Signed-off-by: Rob Herring <robh@kernel.org>