dt-bindings: usb: tegra-xusb: Remove path references

Unresolved path references are now flagged as errors when checking the
device tree binding examples, so convert them into label references.

Reported-by: Conor Dooley <conor.dooley@microchip.com>
Suggested-by: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221130154111.1655603-1-thierry.reding@gmail.com


Signed-off-by: Rob Herring <robh@kernel.org>