dt-bindings: ufs: qcom: document SC8180X UFS

Document already upstreamed and used Qualcomm SC8180x UFS host
controller to fix dtbs_check warnings like:

sc8180x-primus.dtb: ufshc@1d84000: compatible:0: 'qcom,sc8180x-ufshc' is not one of ['qcom,msm8994-ufshc', ... ]
sc8180x-primus.dtb: ufshc@1d84000: Unevaluated properties are not allowed ('compatible' was unexpected)

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

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

···
           - qcom,msm8998-ufshc
           - qcom,sa8775p-ufshc
           - qcom,sc7280-ufshc
+          - qcom,sc8180x-ufshc
           - qcom,sc8280xp-ufshc
           - qcom,sdm845-ufshc
           - qcom,sm6115-ufshc
···
               - qcom,msm8998-ufshc
               - qcom,sa8775p-ufshc
               - qcom,sc7280-ufshc
+              - qcom,sc8180x-ufshc
               - qcom,sc8280xp-ufshc
               - qcom,sm8250-ufshc
               - qcom,sm8350-ufshc