camcontrol: add support for Toshiba drive firmware update

Thanks to Toshiba for providing the SCSI spec for their latest
generation drives so I could confirm how they operate.

The firmware download works in a pretty standard way, so this
is a straightforward table addition.

sbin/camcontrol/camcontrol.8:
Document that Toshiba drives are supported for fwdownload,
and that it was tested on TOSHIBA MG10SFA22TE 22TB drives.

sbin/camcontrol/fwdownload.c:
Add TOSHIBA to the known SCSI vendors list for fwdownload.

Sponsored by: Spectra Logic
MFC after: 3 days