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

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

Cc: Tsahee Zidenberg <tsahee@annapurnalabs.com>
Cc: Antoine Tenart <antoine.tenart@free-electrons.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>