[DECNET]: add memory buffer settings 

The patch (originally from Steve) simply adds memory buffer settings to 
DECnet similar to those in TCP.

Signed-off-by: Patrick Caulfield <patrick@tykepenguin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/dn.h b/include/net/dn.h
index c1dbbd2..a4b6168 100644
--- a/include/net/dn.h
+++ b/include/net/dn.h
@@ -234,4 +234,8 @@
 extern int decnet_dr_count;
 extern int decnet_no_fc_max_cwnd;
 
+extern int sysctl_decnet_mem[3];
+extern int sysctl_decnet_wmem[3];
+extern int sysctl_decnet_rmem[3];
+
 #endif /* _NET_DN_H */