Verify that USB SuperSpeed works along with role switching

!76 (closed) introduces USB "role switch", setting host or peripheral mode according to what the HW finds is actually active and without using OTG. The i.MX 8 reference manual states that SuperSpeed mode is not supported when OTG is enabled, giving rise to OS-issues#129 (closed) and #158 (closed). It would be good to verify that SuperSpeed mode works together with role switching to ensure that neither OS-issues#129 (closed) nor #158 (closed) are indeed needed.