pflowctl: add missing break to case 's'

CID:		1534009
Reported by:	Coverity Scan
Reviewed by:	kp
Differential Revision: https://reviews.freebsd.org/D43704

sbin/pflowctl/pflowctl.c

@@ -577,6 +577,7 @@ main(int argc, char *argv[])
 			op = OP_SET;
 			set_arg_count = argc - optind;
 			set_args = argv + optind;
+			break;
 		case 'v':
 			verbose = true;
 			break;