dt-bindings: phy: mxs-usb-phy: add imx8ulp and imx8qm compatible

The imx8ulp and imx8qm are compatible with imx8dxl. This will add such
compatible.

Signed-off-by: Xu Yang <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/phy/fsl,mxs-usbphy.yaml

···
           - const: fsl,imx6ul-usbphy
           - const: fsl,imx23-usbphy
       - items:
-          - const: fsl,imx8dxl-usbphy
+          - enum:
+              - fsl,imx8dxl-usbphy
+              - fsl,imx8qm-usbphy
+              - fsl,imx8ulp-usbphy
           - const: fsl,imx7ulp-usbphy
 
   reg: