firewire: use split transaction timeout only for split transactions

Instead of starting the split transaction timeout timer when any request
is submitted, start it only when the destination's ACK_PENDING has been
received.  This prevents us from using a timeout that is too short, and,
if the controller's AT queue is emptying very slowly, from cancelling
a packet that has not yet been sent.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

include/linux/firewire.h

@@ -302,9 +302,9 @@ struct fw_packet {
 struct fw_transaction {
 	int node_id; /* The generation is implied; it is always the current. */
 	int tlabel;
-	int timestamp;
 	struct list_head link;
 	struct fw_card *card;
+	bool is_split_transaction;
 	struct timer_list split_timeout_timer;
 
 	struct fw_packet packet;