[dv,usbdev] Data toggle restore sequence

[alees24]

Add a test sequence for the additional Data Toggle restore functionality. This sequence first performs some basic tests using the CSR interface and then brings up the USB connection and tests their interaction with the USB traffic.

Note that the data toggles may safely be changed between packets in the DV environment because the USB traffic is controlled. For active endpoints on a live system they must be modified only under very specific conditions such as halt or reset.