- Store the softc of the device in the 'si_drv1' of the cdev.
- Lookup the softc via 'si_drv1' in cdev methods rather than using the
minor number as a unit for devclass_get_softc().
- Lookup the device_t via the softc field in cdev methods rather than
using the minor number as a unit for devclass_get_device().
- Add a mutex to the softc to protect 'sc_opened'.
- Remove D_NEEDGIANT as all the smbus drivers are now MPSAFE and this driver
is now MPSAFE.
- Remove some checks for NULL softc pointers that can't happen and don't
bzero the softc during attach.
697218c9b6