dt-bindings: arm: Convert VIA board/soc bindings to json-schema

Convert VIA SoC bindings to DT schema format using json-schema.

Cc: Tony Prisk <linux@prisktech.co.nz>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>