dm: Make rt aware

Use the BUG_ON_NORT variant for the irq_disabled() checks. RT has
interrupts legitimately enabled here as we cant deadlock against the
irq thread due to the "sleeping spinlocks" conversion.

Reported-by: Luis Claudio R. Goncalves <lclaudio@uudg.org>

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/md/dm-rq.c

@@ -671,7 +671,7 @@ static void dm_old_request_fn(struct request_queue *q)
 		/* Establish tio->ti before queuing work (map_tio_request) */
 		tio->ti = ti;
 		kthread_queue_work(&md->kworker, &tio->work);
-		BUG_ON(!irqs_disabled());
+		BUG_ON_NONRT(!irqs_disabled());
 	}
 }