net: inet: Remove count from inet_listen_hashbucket

After commit 0ee58dad ("net: tcp6: prefer listeners bound to an address")
and commit d9fbc7f6

 ("net: tcp: prefer listeners bound to an address"),
the count is no longer used.  This patch removes it.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>