dt-bindings: usb: Add bindings for multiport properties on DWC3 controller

Add bindings to indicate properties required to support multiport
on Synopsys DWC3 controller.

Suggested-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230828133033.11988-3-quic_kriskura@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>