dt-bindings: memory-controllers: convert arm,pl172.txt to yaml format

Convert arm,pl172.txt to yaml format.
Additional changes:
- add mpmc,read-enable-delay property.
- allow gpio@addr and sram@addr as child node to match existed dts.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250602141246.941448-1-Frank.Li@nxp.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>