Add SCSI passthrough to CTL

[Bhimanshu Kumar]

*Introduction : *CTL is the FreeBSD SCSI target layer. There are various
SCSI commands, but it's usually used for block-level access. This projects
focuses on making CTL capable of providing physical optical drive as a
whole to the initiator machine
Link : https://github.com/bhimanshu1997/freebsd

Report:
1. added new device in CTL code
2. modified ctld(8) to identify passthrough device

plan for next week
1. adding code in ctld/ctl so that it could convert the device address to
actual device and pass it to CTL backend