test/kvargs: fix invalid cases check

The return was not properly placed, and only the first test case
was validated.

Fixes: e495f54355 ("kvargs: add test case in app/test")
Cc: stable@dpdk.org

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>

app/test/test_kvargs.c

@@ -230,8 +230,8 @@ static int test_invalid_kvargs(void)
 			rte_kvargs_free(kvlist);
 			goto fail;
 		}
-		return 0;
 	}
+	return 0;
 
  fail:
 	printf("while processing <%s>", *args);