mptcp: move MPTCPOPT_HMAC_LEN to net/mptcp.h

Move macro MPTCPOPT_HMAC_LEN definition from net/mptcp/protocol.h to
include/net/mptcp.h.
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/mptcp.h

@@ -39,6 +39,7 @@ struct mptcp_ext {
 			infinite_map:1;
 };
 
+#define MPTCPOPT_HMAC_LEN	20
 #define MPTCP_RM_IDS_MAX	8
 
 struct mptcp_rm_list {
@@ -89,7 +90,7 @@ struct mptcp_out_options {
 			u32 nonce;
 			u32 token;
 			u64 thmac;
-			u8 hmac[20];
+			u8 hmac[MPTCPOPT_HMAC_LEN];
 		};
 	};
 #endif

net/mptcp/protocol.h

@@ -83,7 +83,6 @@
 
 /* MPTCP MP_JOIN flags */
 #define MPTCPOPT_BACKUP		BIT(0)
-#define MPTCPOPT_HMAC_LEN	20
 #define MPTCPOPT_THMAC_LEN	8
 
 /* MPTCP MP_CAPABLE flags */