arm64: dts: qcom: sc7180: Add maximum speed property for DWC3 USB node

Adding maximum speed property for DWC3 USB node which can be used
for setting interconnect bandwidth.

Signed-off-by: Sandeep Maheswaram <sanm@codeaurora.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lore.kernel.org/r/1595317489-18432-3-git-send-email-sanm@codeaurora.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>