irq: Add declaration of irq_domain_simple_ops to irqdomain.h

irq_domain_simple_ops is exported, but is not declared in irqdomain.h,
so add it.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: marc.zyngier@arm.com
Cc: thomas.abraham@linaro.org
Cc: jamie@jamieiles.com
Cc: b-cousson@ti.com
Cc: shawn.guo@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: devicetree-discuss@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1316017900-19918-2-git-send-email-robherring2@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/irqdomain.h

@@ -80,6 +80,7 @@ extern void irq_domain_del(struct irq_domain *domain);
 #endif /* CONFIG_IRQ_DOMAIN */
 
 #if defined(CONFIG_IRQ_DOMAIN) && defined(CONFIG_OF_IRQ)
+extern struct irq_domain_ops irq_domain_simple_ops;
 extern void irq_domain_add_simple(struct device_node *controller, int irq_base);
 extern void irq_domain_generate_simple(const struct of_device_id *match,
 					u64 phys_base, unsigned int irq_start);