net: rename SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA

This patch is a cleanup to make following patch easier to
review.

Goal is to move SOCK_ASYNC_NOSPACE and SOCK_ASYNC_WAITDATA
from (struct socket)->flags to a (struct socket_wq)->flags
to benefit from RCU protection in sock_wake_async()

To ease backports, we rename both constants.

Two new helpers, sk_set_bit(int nr, struct sock *sk)
and sk_clear_bit(int net, struct sock *sk) are added so that
following patch can change their implementation.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index 0aa6fdf..6d4d456 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -125,7 +125,7 @@
 	if (flags & MSG_DONTWAIT)
 		return -EAGAIN;
 
-	set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
+	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 
 	for (;;) {
 		if (signal_pending(current))
@@ -139,7 +139,7 @@
 	}
 	finish_wait(sk_sleep(sk), &wait);
 
-	clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 
 	return err;
 }