dt-bindings: arm: Convert UniPhier System Cache to json-schema

Convert the UniPhier System Cache binding to DT schema format.
This is a full-custom outer cache (L2 and L3) used on UniPhier
ARM 32-bit SoCs.

While I was here, I added the interrupts property. This is not
used in Linux, but the hardware has interrupt lines at least.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Rob Herring <robh@kernel.org>