md: move async_tx_issue_pending_all outside spin_lock_irq

Some dma drivers need to call spin_lock_bh in their device_issue_pending
routines.  This change avoids:

WARNING: at kernel/softirq.c:136 local_bh_enable_ip+0x3a/0x85()

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/md/raid5.c

@@ -3809,10 +3809,8 @@ static void raid5d(mddev_t *mddev)
 
 		sh = __get_priority_stripe(conf);
 
-		if (!sh) {
-			async_tx_issue_pending_all();
+		if (!sh)
 			break;
-		}
 		spin_unlock_irq(&conf->device_lock);
 
 		handled++;
@@ -3825,6 +3823,7 @@ static void raid5d(mddev_t *mddev)
 
 	spin_unlock_irq(&conf->device_lock);
 
+	async_tx_issue_pending_all();
 	unplug_slaves(mddev);
 
 	pr_debug("--- raid5d inactive\n");