mptcp: using TOKEN_MAX_RETRIES instead of magic number

We have macro TOKEN_MAX_RETRIES for the number of token generate retries,
so using TOKEN_MAX_RETRIES in subflow_check_req().

And rename TOKEN_MAX_RETRIES to MPTCP_TOKEN_MAX_RETRIES as it is now
exposed.

Fixes: 535fb8152f31 ("mptcp: token: move retry to caller")
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jianguo Wu <wujianguo@chinatelecom.cn>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
diff --git a/net/mptcp/token.c b/net/mptcp/token.c
index 72a24e6..a98e554 100644
--- a/net/mptcp/token.c
+++ b/net/mptcp/token.c
@@ -33,7 +33,6 @@
 #include <net/mptcp.h>
 #include "protocol.h"
 
-#define TOKEN_MAX_RETRIES	4
 #define TOKEN_MAX_CHAIN_LEN	4
 
 struct token_bucket {
@@ -153,7 +152,7 @@ int mptcp_token_new_connect(struct sock *sk)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
-	int retries = TOKEN_MAX_RETRIES;
+	int retries = MPTCP_TOKEN_MAX_RETRIES;
 	struct token_bucket *bucket;
 
 again: