x86: ioapic: Add io_apic_setup_irq_pin()

There are about four places in the ioapic code which do exactly the
same setup sequence. Also the OF based ioapic setup needs that
function to avoid putting the OF specific code into ioapic.c

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 56dcf08..37dbb3f 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -151,6 +151,8 @@
 extern void ioapic_and_gsi_init(void);
 extern void ioapic_insert_resources(void);
 
+int io_apic_setup_irq_pin(unsigned int irq, int node, struct io_apic_irq_attr *attr);
+
 extern struct IO_APIC_route_entry **alloc_ioapic_entries(void);
 extern void free_ioapic_entries(struct IO_APIC_route_entry **ioapic_entries);
 extern int save_IO_APIC_setup(struct IO_APIC_route_entry **ioapic_entries);