MFC r253476:

MFC r253476:

  Add message when nvd disks are attached and detached.

  As part of this commit, add an nvme_strvis() function which borrows
  heavily from cam_strvis().  This will allow stripping of
  leading/trailing whitespace and also handle unprintable characters
  in model/serial numbers.  This function goes into a new nvme_util.c
  file which is used by both the driver and nvmecontrol.

Approved by:	re (kib)
Sponsored by:	Intel

git-svn-id: svn://svn.freebsd.org/base/stable/9@253631 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f