trace: tcp: Add const qualifier to skb parameter in tcp_probe event

Change the tcp_probe tracepoint to accept a const struct sk_buff
parameter instead of a non-const one. This improves type safety and
better reflects that the skb is not modified within the tracepoint
implementation.

Signed-off-by: Breno Leitao <[email protected]>
Reviewed-by: Kuniyuki Iwashima <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: leitao

include/trace/events/tcp.h

@@ -293,7 +293,7 @@ DECLARE_TRACE(tcp_cwnd_reduction_tp,
 
 TRACE_EVENT(tcp_probe,
 
-	TP_PROTO(struct sock *sk, struct sk_buff *skb),
+	TP_PROTO(struct sock *sk, const struct sk_buff *skb),
 
 	TP_ARGS(sk, skb),