Fix LUN discovery for targets that don't support REPORT_LUNS, broken
in r263741.  At least with CTL (slightly modified to report SPC2) there
is still some problem: it doesn't seem to find LUNs higher than 7.

Sponsored by:	The FreeBSD Foundation


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271703 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f