dt-bindings: usb: hcd: add missing phy name to example

The example host controller node has two PHYs and therefore needs two
PHY names.

Fixes: 3aa3c66a

 ("dt-bindings: usb: Bring back phy-names")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231110134802.32060-1-johan+linaro@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>