dt-bindings: mfd: Convert aspeed,ast2400-p2a-ctrl to DT schema

Convert the aspeed,ast2x00-p2a-ctrl binding to DT schema format. The schema
is simple enough to just add it to the parent aspeed,ast2x00-scu binding.

Signed-off-by: "Rob Herring (Arm)" <robh@kernel.org>
Acked-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20250829230450.1496151-1-robh@kernel.org


Signed-off-by: Lee Jones <lee@kernel.org>