dt-bindings: dma: qcom: gpi: add compatible for sdm670

The Snapdragon 670 uses GPI DMA for its GENI interface. Add a compatible
string for it in the documentation.

Signed-off-by: Richard Acayan <mailingradian@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221018005740.23952-3-mailingradian@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>