Comment out some pointless device open/close around reading device IDs.

FreeBSD ZFS port unlike OpenSolaris does not use device IDs, and does not
implement respective devid_*() fuctions.  It is pointless to open devices
just to close them back immediately.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
Fix -width argument to Bl -tag.
Simplify code slightly. Passing an array by &array[0] does work, but is
silly.