scsi: devinfo: fix format of the device list

Replace "" with NULL for product revision level, and merge TEXEL
duplicate entries.

Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
Cc: SCSI ML <linux-scsi@vger.kernel.org>
Signed-off-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>