freed memory cannot be used during detach.
- Remove all panic() calls from the urtw driver because
panic() is not appropriate here.
- Remove redundant checks for device detached in
device detach callbacks.
- Use DEVMETHOD_END to mark end of device methods.
MFC after: 2 weeks
through the USB API and/or busdma.
The following assumptions have been made:
umass - buffers passed from CAM/SCSI layer are OK
network - mbufs are OK.
Some other nits while at it.
MFC after: 1 week
Suggested by: imp
