USB Mass Storage: Display target number for SCM USB-SCSI converters

The USB Mass Storage Class (Bulk Only Transport) has the LUN in bits [3:0] of byte 13 of the command block wrapper. Bits [7:4] of that byte are undefined/reserved.

USB-SCSI converters based on a chipset from SCM Microsystems can work with multiple SCSI devices. After enabling multi-target mode (which the vendor driver and Linux do), the target number is given in bits [6:4] of CBW byte 13.

Request from Mark

Bug:10563
Change-Id: I8e6d9b7d47ff4296d41e8b9b15f4bd44c89238c9
Reviewed-on: https://code.wireshark.org/review/4625
Reviewed-by: Anders Broman <a.broman58@gmail.com>