USB fails on hubs without TT

[xobs]

When a hub has no transaction translator, USB relies on the "address" field to determine which device to talk to.

Currently, foboot ignores the "address" field and assumes it's on a switched hub with a transaction translator. Such devices are rare in modern computing, so the workaround is to put Fomu into a downstream hub. However, we should add SET_ADDRESS support to fix these devices.