[DECNET]: Another unnecessary net/tcp.h inclusion in net/dn.h

No longer needed.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/dn.h

@@ -3,7 +3,6 @@
 
 #include <linux/dn.h>
 #include <net/sock.h>
-#include <net/tcp.h>
 #include <asm/byteorder.h>
 
 #define dn_ntohs(x) le16_to_cpu(x)