arm64: dts: qcom: sc7280: Add wakeup-source property for USB node

Adding wakeup-source property for USB controller in SC7280.
This property is added to inform that the USB controller is
wake up capable and to conditionally power down the phy during
system suspend.

Signed-off-by: Sandeep Maheswaram <quic_c_sanm@quicinc.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/1649704614-31518-7-git-send-email-quic_c_sanm@quicinc.com