tcp: convert tcp_md5_needed to static_branch API

We prefer static_branch_unlikely() over static_key_false() these days.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e2fa6eb..ad07dd7 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3699,7 +3699,7 @@ bool tcp_alloc_md5sig_pool(void)
 		if (!tcp_md5sig_pool_populated) {
 			__tcp_alloc_md5sig_pool();
 			if (tcp_md5sig_pool_populated)
-				static_key_slow_inc(&tcp_md5_needed);
+				static_branch_inc(&tcp_md5_needed);
 		}
 
 		mutex_unlock(&tcp_md5sig_mutex);