Correct some XHCI streams mode transfer handling found by code inspection.
The existing streams mode support is not working and has not been tested
due to lack of hardware which supports the given feature.

MFC after:	1 week
Use LIST_EMPTY when appropriate.

MFC after: 1 week
Don't set the start ISOC ASAP bit for non-isochronous TRBs.

MFC after:	1 week