sr_vendor: support Beurer GL50 evo CD-on-a-chip devices.

The Beurer GL50 evo uses a Cygnal-manufactured CD-on-a-chip that only
accepts a subset of SCSI commands, and supports neither audio commands
nor generic packet commands.

Actually sending those commands bring the device to an unrecoverable
state that causes the device to hang and reset.

To: Jens Axboe <axboe@kernel.dk>
Cc: linux-kernel@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Diego Elio Pettenò <flameeyes@flameeyes.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>