selftests: Fix the if conditions of in test_extra_filter()

The socket 2 bind the addr in use, bind should fail with EADDRINUSE. So
if bind success or errno != EADDRINUSE, testcase should be failed.

Fixes: 3ca8e402

 ("soreuseport: BPF selection functional test")
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Link: https://lore.kernel.org/r/1663916557-10730-1-git-send-email-wangyufen@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>