xfrm: Fix bucket count reported to userspace

sadhcnt is reported by `ip -s xfrm state count` as "buckets count", not the
hash mask.

Fixes: 28d8909b ("[XFRM]: Export SAD info.")
Signed-off-by: Benjamin Poirier <bpoirier@suse.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_state.c

@@ -788,7 +788,7 @@ void xfrm_sad_getinfo(struct net *net, struct xfrmk_sadinfo *si)
 {
 	spin_lock_bh(&net->xfrm.xfrm_state_lock);
 	si->sadcnt = net->xfrm.state_num;
-	si->sadhcnt = net->xfrm.state_hmask;
+	si->sadhcnt = net->xfrm.state_hmask + 1;
 	si->sadhmcnt = xfrm_state_hashmax;
 	spin_unlock_bh(&net->xfrm.xfrm_state_lock);
 }