dt-bindings: net: qcom,ipa: add SM8550 compatible

Add support for SM8550, which uses IPA v5.5.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>