scsi: mpt3sas: make driver options visible in sys

Support is easier with all driver parameters visible in sysfs.  Also I've
replaced a constant with an octal permission.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Suganath Prabu <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>