[PATCH net-next] mptcp: Remove set but not used variable 'can_ack'

[YueHaibing]

Fixes gcc '-Wunused-but-set-variable' warning:

net/mptcp/options.c: In function 'mptcp_established_options_dss':
net/mptcp/options.c:338:7: warning:
 variable 'can_ack' set but not used [-Wunused-but-set-variable]

commit dc093db5cc05 ("mptcp: drop unneeded checks")
leave behind this unused, remove it.

Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 net/mptcp/options.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 63c8ee49cef2..8ba34950241c 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -335,7 +335,6 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 	struct mptcp_sock *msk;
 	unsigned int ack_size;
 	bool ret = false;
-	bool can_ack;
 	u8 tcp_fin;
 
 	if (skb) {
@@ -364,7 +363,6 @@ static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
 	/* passive sockets msk will set the 'can_ack' after accept(), even
 	 * if the first subflow may have the already the remote key handy
 	 */
-	can_ack = true;
 	opts->ext_copy.use_ack = 0;
 	msk = mptcp_sk(subflow->conn);
 	if (!READ_ONCE(msk->can_ack)) {