selftests/bpf: fix unintentional switch case fall through

Break from switch expression after parsing -n CLI argument in veristat,
instead of falling through and enabling comparison mode.
Fixes: a5c57f8 ("veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag")

Signed-off-by: Mykyta Yatsenko <[email protected]>
Acked-by: Yonghong Song <[email protected]>

Author: mykyta5

tools/testing/selftests/bpf/veristat.c

@@ -364,6 +364,7 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 			fprintf(stderr, "invalid top N specifier: %s\n", arg);
 			argp_usage(state);
 		}
+		break;
 	case 'C':
 		env.comparison_mode = true;
 		break;