MFC r235911, r235980, r238739, r238740, r238894, r239213, r241488, r241952,

MFC r235911, r235980, r238739, r238740, r238894, r239213, r241488, r241952,
r242173, r242621, r242634, r242638, r242647, r242720, r244418, r244508,
r245891:
Revamp the CAM enclosure services driver.
This updated driver uses an in-kernel daemon to track state changes and
publishes physical path location information for disk elements into the
CAM device database.

Sponsored by:   Spectra Logic Corporation
Sponsored by:   iXsystems, Inc.

git-svn-id: svn://svn.freebsd.org/base/stable/9@246437 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f