net: make sock_inuse_add() available

commit d477eb90 upstream.

MPTCP hard codes it, let us instead provide this helper.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
[ cherry-pick from amazon-linux amazon-5.15.y/mainline ]
Link: https://github.com/amazonlinux/linux/commit/7154d8eaac16


Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>