tcp: simplify endpoint creation at the passive side

Use the intended TCP stack when creating a TCP endpoint instead of
creating it the endpoint the default stack first and after that
switching it to use the intended TCP stack.

Reviewed by: Peter Lei, rrs and jtl (older version)
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D45411

(cherry picked from commit baee801c92d26f4b7d1b2a9edd755c1b07b84167)