arm64: dts: qcom: sc7280: Add GPI DMA compatible fallback

Use SM6350 as fallback for GPI DMA, to indicate devices are compatible
and that drivers can bind with only one compatible.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221018230352.1238479-4-krzysztof.kozlowski@linaro.org