scsi: Use 'blist_flags_t' for scsi_devinfo flags

As per recommendation from Linus we should be using a distinct type for
blacklist flags.

[mkp: was cut against an older kernel, applied by hand]

Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>