MFC r255501

This is slightly modified from the FreeBSD/head version, to include
version checks for the scanning changes for not only FreeBSD/head
(1000039 and higher) but also stable/9 (902502 and higher).

  ------------------------------------------------------------------------
  r255501 | ken | 2013-09-12 16:06:12 -0600 (Thu, 12 Sep 2013) | 18 lines

  Fix an issue that caused Integrated RAID volumes on LSI mps(4) controllers
  to not get scanned on boot.

  The problem originated in change 253549.  With the change to the mps(4)
  driver to scan only targets that it knows it has (as opposed to scanning
  the entire bus), scanning RAID volumes on boot was omitted.

  So, for versions of FreeBSD that have the scanning changes
  (__FreeBSD_version 1000039 and higher), scan RAID volumes that are added
  whether or not we're booting.

  PR:             kern/181784
  Reported by:    Xiguang Wang <kurapica@gmail.com>
  Tested by:      Dennis Glatting <dg@pki2.com>
  Sponsored by:   Spectra Logic

PR:		kern/181784