dt-bindings: memory-controllers: reference TI GPMC peripheral properties

Reference the Texas Instruments GPMC Bus Child Nodes schema with
peripheral properties, in common Memory Controller bus
Peripheral-specific schema, to allow properly validate devices like
davicom,dm9000.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713152848.82752-3-krzysztof.kozlowski@linaro.org


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