dt-bindings: ufs: qcom: document SM6125 UFS

Document already upstreamed and used Qualcomm SM6125 UFS host controller to fix
dtbs_check warnings like:

sm6125-xiaomi-laurel-sprout.dtb: ufs@4804000: compatible:0: 'qcom,sm6125-ufshc' is not one of ['qcom,msm8994-ufshc', ...
sm6125-xiaomi-laurel-sprout.dtb: ufs@4804000: Unevaluated properties are not allowed ('compatible' was unexpected)

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Martin Botka <[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,sc8280xp-ufshc
           - qcom,sdm845-ufshc
           - qcom,sm6115-ufshc
+          - qcom,sm6125-ufshc
           - qcom,sm6350-ufshc
           - qcom,sm8150-ufshc
           - qcom,sm8250-ufshc
···
           contains:
             enum:
               - qcom,sm6115-ufshc
+              - qcom,sm6125-ufshc
     then:
       properties:
         clocks: