Revert "net: inet: Remove count from inet_listen_hashbucket"

This reverts commit bb9bcf47 which is
commit 8ea1eebb upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I7312d7514465b14b40fbc96f35d15a3af057168e
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>