scsi: mpt3sas: open-code _scsih_scsi_lookup_get()

Just a wrapper around the scsi lookup array and only used in one place,
so open-code it.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>