kernel/irq/irqdomain.c: before use 'irq_data', need check it whether valid.

Since irq_data may be NULL, if so, we WARN_ON(), and continue, 'hwirq'
which related with 'irq_data' has to initialize later, or it will cause
issue.
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

kernel/irq/irqdomain.c

@@ -398,11 +398,12 @@ static void irq_domain_disassociate_many(struct irq_domain *domain,
 	while (count--) {
 		int irq = irq_base + count;
 		struct irq_data *irq_data = irq_get_irq_data(irq);
-		irq_hw_number_t hwirq = irq_data->hwirq;
+		irq_hw_number_t hwirq;
 
 		if (WARN_ON(!irq_data || irq_data->domain != domain))
 			continue;
 
+		hwirq = irq_data->hwirq;
 		irq_set_status_flags(irq, IRQ_NOREQUEST);
 
 		/* remove chip and handler */