dt-bindings: phy: imx8mq-usb: correct reference to usb-switch.yaml

The i.MX95 usb-phy can work with or without orientation-switch. With
current setting, if usb-phy works without orientation-switch, the
dt-schema check will show below error:

phy@4c1f0040: 'oneOf' conditional failed, one must be fixed:
'port' is a required property
'ports' is a required property
from schema $id: http://devicetree.org/schemas/phy/fsl,imx8mq-usb-phy.yaml#

This will correct the behavior of referring to usb-switch.yaml.

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

Documentation/devicetree/bindings/phy/fsl,imx8mq-usb-phy.yaml

···
           maxItems: 1
 
   - if:
-      properties:
-        compatible:
-          contains:
-            enum:
-              - fsl,imx95-usb-phy
+      required:
+        - orientation-switch
     then:
       $ref: /schemas/usb/usb-switch.yaml#