irqchipr/i8259: Mark i8259_of_init() static

i8259_of_init() is only used as an initcall and does not need to be global,
so mark it static to avoid:

drivers/irqchip/irq-i8259.c:343:12: warning: no previous prototype for 'i8259_of_init' [-Wmissing-prototypes]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230810123404.1222332-3-arnd@kernel.org

drivers/irqchip/irq-i8259.c

@@ -340,7 +340,7 @@ static void i8259_irq_dispatch(struct irq_desc *desc)
 	generic_handle_domain_irq(domain, hwirq);
 }
 
-int __init i8259_of_init(struct device_node *node, struct device_node *parent)
+static int __init i8259_of_init(struct device_node *node, struct device_node *parent)
 {
 	struct irq_domain *domain;
 	unsigned int parent_irq;