tracing, net: fix net tree and tracing tree merge interaction

Today's linux-next build (powerpc ppc64_defconfig) failed like this:

 In file included from net/core/skbuff.c:69:
 include/trace/skb.h:4: error: expected ')' before '(' token
 include/trace/skb.h:4: error: expected ')' before '(' token
 [...]

Caused by commit 2939b04 ("tracing:
replace TP<var> with TP_<var>") from the tracing tree interacting with
commit 4893d39 ("Network Drop Monitor:
Add trace declaration for skb frees") from the net tree.

Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/trace/skb.h

@@ -5,7 +5,7 @@
 #include <linux/tracepoint.h>
 
 DECLARE_TRACE(kfree_skb,
-	TPPROTO(struct sk_buff *skb, void *location),
-	TPARGS(skb, location));
+	TP_PROTO(struct sk_buff *skb, void *location),
+	TP_ARGS(skb, location));
 
 #endif