genirq/irqdomain: Remove WARN_ON() on out-of-memory condition

There is no need to print a backtrace when memory allocation fails, as
the memory allocation core already takes care of that.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/20190527115742.2693-1-geert+renesas@glider.be

kernel/irq/irqdomain.c

@@ -139,7 +139,7 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
 
 	domain = kzalloc_node(sizeof(*domain) + (sizeof(unsigned int) * size),
 			      GFP_KERNEL, of_node_to_nid(of_node));
-	if (WARN_ON(!domain))
+	if (!domain)
 		return NULL;
 
 	if (fwnode && is_fwnode_irqchip(fwnode)) {