dt-bindings: usb: Add new compatible string for AM64 SoC

Add compatible string in j721e-usb binding file as the same USB subsystem
is present in AM64.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20201215042549.7956-1-a-govindraju@ti.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/ti,j721e-usb.yaml

@@ -11,8 +11,12 @@ maintainers:
 
 properties:
   compatible:
-    items:
+    oneOf:
       - const: ti,j721e-usb
+      - const: ti,am64-usb
+      - items:
+          - const: ti,j721e-usb
+          - const: ti,am64-usb
 
   reg:
     description: module registers