selftests: tls: test for correct proto_ops

Previous patch fixes overriding callbacks incorrectly. Triggering
the crash in sendpage_locked would be more spectacular but it's
hard to get to, so take the easier path of proving this is broken
and call getname. We're currently getting IPv4 socket info on an
IPv6 socket.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>