irqchip/irq-bcm7038-l1: Make bcm7038_l1_of_init() static

Fix the following sparse warning:

drivers/irqchip/irq-bcm7038-l1.c:419:12: warning: symbol
'bcm7038_l1_of_init' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200417074036.46594-1-yanaijie@huawei.com

drivers/irqchip/irq-bcm7038-l1.c

@@ -416,7 +416,7 @@ static const struct irq_domain_ops bcm7038_l1_domain_ops = {
 	.map			= bcm7038_l1_map,
 };
 
-int __init bcm7038_l1_of_init(struct device_node *dn,
+static int __init bcm7038_l1_of_init(struct device_node *dn,
 			      struct device_node *parent)
 {
 	struct bcm7038_l1_chip *intc;