[SCSI] Mask capabilities for SCSI-1 CD drive

SCSI-1 CD drives can't do MRW or be opened for writing, so mask off
those capabilities.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Acked-by: Jens Axboe <axboe@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>