Fix old iSCSI initiator to work with new CAM locking.

This switches code to using xpt_scan() routine, irrelevant to locking.
Using xpt_action() directly requires knowledge about higher level locks,
that SIM does not need to have.

This code is obsoleted, but that is not a reason to crash.

MFC after:	3 days


git-svn-id: svn+ssh://svn.freebsd.org/base/head@272308 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f