Most of the implementation is the same as the SuperSpeed (SS) case. One
difference is that an SSP hub reports its through the SuperSpeedPlus
USB Device Capability descriptor in the BOS descriptor.
This descriptor provides the link speed for both the TX and RX lanes.
Currently, we determine the effective link speed using the slowest link
segment in the path.
According to the USB 3.2 specification, this descriptor is mandatory.