MFC r260588 and r260589:

MFC r260588 and r260589:
- Separate I/O errors from reception of STALL PID.
- Implement better error recovery for Transaction Translators, TTs,
found in High Speed USB HUBs which translate from High Speed USB into
FULL or LOW speed USB. In some rare cases SPLIT transactions might get
lost, which might leave the TT in an unknown state. Whenever we detect
such an error try to issue either a clear TT buffer request, or if
that is not possible reset the whole TT.

git-svn-id: svn://svn.freebsd.org/base/stable/8@261107 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f