scsi-trace: remove service action definitions

scsi_opcode_name() is displaying the opcode, not the service
action.

Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>