dt-bindings: phy: qcom,snps-eusb2: document the Milos Synopsys eUSB2 PHY

Document the Synopsys eUSB2 PHY on the Milos SoC by using the SM8550 as
fallback.

Acked-by: Krzysztof Kozlowski <[e-mail]>
Signed-off-by: Luca Weiss <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/phy/qcom,snps-eusb2-phy.yaml

···
     oneOf:
       - items:
           - enum:
+              - qcom,milos-snps-eusb2-phy
               - qcom,sar2130p-snps-eusb2-phy
               - qcom,sdx75-snps-eusb2-phy
               - qcom,sm8650-snps-eusb2-phy