hyper-v: trace channel events

Added an additional set of trace points for when channel gets notified
or signals host.

Suggested-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/connection.c

@@ -322,6 +322,8 @@ void vmbus_on_event(unsigned long data)
 	struct vmbus_channel *channel = (void *) data;
 	unsigned long time_limit = jiffies + 2;
 
+	trace_vmbus_on_event(channel);
+
 	do {
 		void (*callback_fn)(void *);