ARM: dts: pxa: use new 'dma-channels/requests' properties

The '#dma-channels' and '#dma-requests' properties were deprecated in
favor of these defined by generic dma-common DT bindings.  Add new
properties while keeping old ones for backwards compatibility.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220516142857.6419-2-krzysztof.kozlowski@linaro.org

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>