Make the hpt27xx(4) driver MPSAFE.
- Use the existing vbus locks instead of Giant for the CAM sim lock.
- Use callout(9) instead of timeout(9).
- Mark the interrupt handler as MPSAFE.
- Don't attempt to pass data in the softc from probe() to attach().

Reviewed by:	Steve Chang <ychang@highpoint-tech.com>
Assisted by:	delphij