irqdomain: Make irq_domain_simple_map() static.

Presently irq_domain_simple_map() isn't labelled as static, but there's
no definition for it in the public irqdomain header either. At present
all in-tree ->map users have meaningful work to do, and all others are
using irq_domain_simple_ops directly. Make it static for now, as it can
always be exported and added to the public API later.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

kernel/irq/irqdomain.c

@@ -758,7 +758,7 @@ static int __init irq_debugfs_init(void)
 __initcall(irq_debugfs_init);
 #endif /* CONFIG_IRQ_DOMAIN_DEBUG */
 
-int irq_domain_simple_map(struct irq_domain *d, unsigned int irq,
+static int irq_domain_simple_map(struct irq_domain *d, unsigned int irq,
 				 irq_hw_number_t hwirq)
 {
 	return 0;