decnet: Use TCP nagle macro instead of literal number in decnet

Use existing TCP nagle macro TCP_NAGLE_OFF and TCP_NAGLE_CORK instead
of the literal number 1 and 2 in the current decnet codes.
Signed-off-by: NGao Feng <fgao@ikuai8.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/decnet/af_decnet.c

@@ -132,6 +132,7 @@ Version 0.0.6    2.1.110   07-aug-98   Eduardo Marcelo Serrat
 #include <net/neighbour.h>
 #include <net/dst.h>
 #include <net/fib_rules.h>
+#include <net/tcp.h>
 #include <net/dn.h>
 #include <net/dn_nsp.h>
 #include <net/dn_dev.h>
@@ -1468,18 +1469,18 @@ static int __dn_setsockopt(struct socket *sock, int level,int optname, char __us
 	case DSO_NODELAY:
 		if (optlen != sizeof(int))
 			return -EINVAL;
-		if (scp->nonagle == 2)
+		if (scp->nonagle == TCP_NAGLE_CORK)
 			return -EINVAL;
-		scp->nonagle = (u.val == 0) ? 0 : 1;
+		scp->nonagle = (u.val == 0) ? 0 : TCP_NAGLE_OFF;
 		/* if (scp->nonagle == 1) { Push pending frames } */
 		break;
 
 	case DSO_CORK:
 		if (optlen != sizeof(int))
 			return -EINVAL;
-		if (scp->nonagle == 1)
+		if (scp->nonagle == TCP_NAGLE_OFF)
 			return -EINVAL;
-		scp->nonagle = (u.val == 0) ? 0 : 2;
+		scp->nonagle = (u.val == 0) ? 0 : TCP_NAGLE_CORK;
 		/* if (scp->nonagle == 0) { Push pending frames } */
 		break;
 
@@ -1607,14 +1608,14 @@ static int __dn_getsockopt(struct socket *sock, int level,int optname, char __us
 	case DSO_NODELAY:
 		if (r_len > sizeof(int))
 			r_len = sizeof(int);
-		val = (scp->nonagle == 1);
+		val = (scp->nonagle == TCP_NAGLE_OFF);
 		r_data = &val;
 		break;
 
 	case DSO_CORK:
 		if (r_len > sizeof(int))
 			r_len = sizeof(int);
-		val = (scp->nonagle == 2);
+		val = (scp->nonagle == TCP_NAGLE_CORK);
 		r_data = &val;
 		break;