ARM: dts: hisilicon: fix errors detected by syscon.yaml

The DT binding for system controller is not allowed to contain only the
compatible string "syscon", the Hisilicon peripheral subsystem controller
should add compatible string "hisilicon,peri-subctrl". Otherwise, the
error "compatible: ['syscon'] is too short" will be reported.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>