firewire: unnecessary BM delay after generation rollover

Noticed by Jarod Wilson:  The bus manager work was unnecessarily delayed
each time the bus generation counter rolled over.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Jarod Wilson <jwilson@redhat.com>
diff --git a/drivers/firewire/fw-card.c b/drivers/firewire/fw-card.c
index 6bd91a1..17a80ce 100644
--- a/drivers/firewire/fw-card.c
+++ b/drivers/firewire/fw-card.c
@@ -232,7 +232,7 @@
 	root_id = root_node->node_id;
 	grace = time_after(jiffies, card->reset_jiffies + DIV_ROUND_UP(HZ, 10));
 
-	if (card->bm_generation + 1 == generation ||
+	if (is_next_generation(generation, card->bm_generation) ||
 	    (card->bm_generation != generation && grace)) {
 		/*
 		 * This first step is to figure out who is IRM and