dt-bindings: soundwire: qcom: Document v3.1.0 version of IP block

Add bindings for Soundwire controllers v3.1.0, which is available on
Qualcomm Glymur SoC.

Signed-off-by: Srinivas Kandagatla <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Tested-by: Alexey Klimov <[e-mail]> # sm8550
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/soundwire/qcom,soundwire.yaml

···
           - qcom,soundwire-v1.6.0
           - qcom,soundwire-v1.7.0
           - qcom,soundwire-v2.0.0
+          - qcom,soundwire-v3.1.0
       - items:
           - enum:
               - qcom,soundwire-v2.1.0