powerpc/6xx: add missing iounmap() on error in hlwd_pic_init()

Add the missing iounmap() before return from hlwd_pic_init()
in the error handling case.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Scott Wood <scottwood@freescale.com>

arch/powerpc/platforms/embedded6xx/hlwd-pic.c

@@ -181,6 +181,7 @@ struct irq_domain *hlwd_pic_init(struct device_node *np)
 					   &hlwd_irq_domain_ops, io_base);
 	if (!irq_domain) {
 		pr_err("failed to allocate irq_domain\n");
+		iounmap(io_base);
 		return NULL;
 	}