xfrm: Fix esn sequence number diff calculation in xfrm_replay_notify_esn()

Commit 0017c0b "xfrm: Fix replay notification for esn." is off by one
for the sequence number wrapped case as UINT_MAX is 0xffffffff, not
0x100000000. ;)

Just calculate the diff like done everywhere else in the file.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_replay.c

@@ -359,14 +359,12 @@ static void xfrm_replay_notify_esn(struct xfrm_state *x, int event)
 		if (replay_esn->seq_hi == preplay_esn->seq_hi)
 			seq_diff = replay_esn->seq - preplay_esn->seq;
 		else
-			seq_diff = UINT_MAX - preplay_esn->seq
-				   + replay_esn->seq;
+			seq_diff = ~preplay_esn->seq + replay_esn->seq + 1;
 
 		if (replay_esn->oseq_hi == preplay_esn->oseq_hi)
 			oseq_diff = replay_esn->oseq - preplay_esn->oseq;
 		else
-			oseq_diff = UINT_MAX - preplay_esn->oseq
-				    + replay_esn->oseq;
+			oseq_diff = ~preplay_esn->oseq + replay_esn->oseq + 1;
 
 		if (seq_diff < x->replay_maxdiff &&
 		    oseq_diff < x->replay_maxdiff) {