firewire: normalize style of queue_work wrappers

A few stylistic changes to unify some code patterns in the subsystem:

  - The similar queue_delayed_work helpers fw_schedule_bm_work,
    schedule_iso_resource, and sbp2_queue_work now have the same call
    convention.
  - Two conditional calls of schedule_iso_resource are factored into
    another small helper.
  - An sbp2_target_get helper is added as counterpart to
    sbp2_target_put.

Object size of firewire-core is decreased a little bit, object size of
firewire-sbp2 remains unchanged.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c
index 98dbbda..d485cdd 100644
--- a/drivers/firewire/sbp2.c
+++ b/drivers/firewire/sbp2.c
@@ -820,20 +820,25 @@
 	fw_device_put(device);
 }
 
-static struct workqueue_struct *sbp2_wq;
+static void sbp2_target_get(struct sbp2_target *tgt)
+{
+	kref_get(&tgt->kref);
+}
 
 static void sbp2_target_put(struct sbp2_target *tgt)
 {
 	kref_put(&tgt->kref, sbp2_release_target);
 }
 
+static struct workqueue_struct *sbp2_wq;
+
 /*
  * Always get the target's kref when scheduling work on one its units.
  * Each workqueue job is responsible to call sbp2_target_put() upon return.
  */
 static void sbp2_queue_work(struct sbp2_logical_unit *lu, unsigned long delay)
 {
-	kref_get(&lu->tgt->kref);
+	sbp2_target_get(lu->tgt);
 	if (!queue_delayed_work(sbp2_wq, &lu->work, delay))
 		sbp2_target_put(lu->tgt);
 }