camcontrol: In defects make -S actually imply 12-byte command

camcontrol(8) says that -S to start at a different offset implies that
we're using the 12 byte command. But really, we're using the 10-byte
command. Fix this by setting use_12byte for -S.

Sponsored by:		Netflix
Reviewed by:		mav
Differential Revision:	https://reviews.freebsd.org/D40526

sbin/camcontrol/camcontrol.c

@@ -3895,6 +3895,7 @@ readdefects(struct cam_device *device, int argc, char **argv,
 				warnx("invalid starting offset %s", optarg);
 				goto defect_bailout;
 			}
+			use_12byte = true;
 			break;
 		}
 		case 'X':