tipc: remove meaningless assignment in Makefile

There is no module named tipc_diag.

The assignment to tipc_diag-y has no effect.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/Makefile b/net/tipc/Makefile
index 1603f5b4..ee49a9f 100644
--- a/net/tipc/Makefile
+++ b/net/tipc/Makefile
@@ -20,5 +20,3 @@
 
 
 obj-$(CONFIG_TIPC_DIAG)	+= diag.o
-
-tipc_diag-y	:= diag.o