devlink: add hardware messages tracing facility

Define a tracepoint and allow user to trace messages going to and from
hardware associated with devlink instance.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/devlink.c

@@ -26,6 +26,10 @@
 #include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/devlink.h>
+#define CREATE_TRACE_POINTS
+#include <trace/events/devlink.h>
+
+EXPORT_TRACEPOINT_SYMBOL_GPL(devlink_hwmsg);
 
 static LIST_HEAD(devlink_list);