[SCSI] hpsa: only do device rescan for certain events

Do no rescan on every events -- way too many rescans are
triggered if we don't filter the events.  Limit rescans
to be triggered by the following set of events:

 * controller state change
 * enclosure hot plug
 * physical drive state change
 * logical drive state change
 * redundant controller state change
 * accelerated io enabled/disabled
 * accelerated io configuration change

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/hpsa.c

@@ -6419,7 +6419,7 @@ static void hpsa_ctlr_needs_rescan(struct ctlr_info *h)
 		return;
 
 	h->events = readl(&(h->cfgtable->event_notify));
-	if (!h->events && !h->drv_req_rescan)
+	if (!(h->events & RESCAN_REQUIRED_EVENT_BITS) && !h->drv_req_rescan)
 		return;
 
 	/*