This patch fixes an issue that uninitialized 'success'
is used to be compared with '0'.
Coverity issue: 337676
Fixes: 3340202f5954 ("stack: add lock-free implementation")
Cc: stable@dpdk.org
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>