dt-bindings: phy: Add QMP PCIe PHY comptible for SM8550

Document the QMP PCIe PHY compatible for SM8550.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20230208180020.2761766-2-abel.vesa@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>