firewire: fw-sbp2: use device generation, not card generation

There was a small window where a login or reconnect job could use an
already updated card generation with an outdated node ID.  We have to
use the fw_device.generation here, not the fw_card.generation, because
the generation must never be newer than the node ID when we emit a
transaction.  This cannot be guaranteed with fw_card.generation.

Furthermore, the target's and initiator's node IDs can be obtained from
fw_device and fw_card.  Dereferencing their underlying topology objects
is not necessary.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

Verified in concert with subsequent memory barriers patch to fix 'giving
up on config rom' issues on multiple system and drive combinations that
were previously affected.
Signed-off-by: Jarod Wilson <jwilson@redhat.com>

drivers/firewire/fw-sbp2.c

@@ -661,9 +661,9 @@ static void sbp2_login(struct work_struct *work)
 	struct sbp2_login_response response;
 	int generation, node_id, local_node_id;
 
-	generation    = device->card->generation;
-	node_id       = device->node->node_id;
-	local_node_id = device->card->local_node->node_id;
+	generation    = device->generation;
+	node_id       = device->node_id;
+	local_node_id = device->card->node_id;
 
 	if (sbp2_send_management_orb(lu, node_id, generation,
 				SBP2_LOGIN_REQUEST, lu->lun, &response) < 0) {
@@ -911,9 +911,9 @@ static void sbp2_reconnect(struct work_struct *work)
 	struct fw_device *device = fw_device(unit->device.parent);
 	int generation, node_id, local_node_id;
 
-	generation    = device->card->generation;
-	node_id       = device->node->node_id;
-	local_node_id = device->card->local_node->node_id;
+	generation    = device->generation;
+	node_id       = device->node_id;
+	local_node_id = device->card->node_id;
 
 	if (sbp2_send_management_orb(lu, node_id, generation,
 				     SBP2_RECONNECT_REQUEST,