dt-bindings: usb: dwc3-xilinx: add optional property reset-gpios

Added optional property support reset-gpios for the dwc3-Xilinx
glue driver.

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220504075309.6244-2-piyush.mehta@xilinx.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>