dt-bindings: usb: dwc3: Add wakeup-source property support

Added support for wakeup-source property. This property can be
used to check and power down the phy during system suspend if
wake up is not supported.

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sandeep Maheswaram <quic_c_sanm@quicinc.com>
Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Link: https://lore.kernel.org/r/1655094654-24052-2-git-send-email-quic_kriskura@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>