x86, io_apic: Introduce set_affinity function pointer

With interrupt remapping a special function is used to
change the affinity of an IO-APIC interrupt. Abstract this
with a function pointer.

Signed-off-by: Joerg Roedel <joro@8bytes.org>
Acked-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/kernel/x86_init.c

@@ -126,4 +126,5 @@ struct x86_io_apic_ops x86_io_apic_ops = {
 	.modify			= native_io_apic_modify,
 	.disable		= native_disable_io_apic,
 	.print_entries		= native_io_apic_print_entries,
+	.set_affinity		= native_ioapic_set_affinity,
 };