x86-32, NUMA: Make apic->x86_32_numa_cpu_node() optional

NUMAQ is the only meaningful user of this callback and
setup_local_APIC() the only callsite.  Stop torturing everyone else by
making the callback optional and removing all the boilerplate
implementations and assignments.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>

arch/x86/kernel/apic/apic_noop.c

@@ -119,14 +119,6 @@ static void noop_apic_write(u32 reg, u32 v)
 	WARN_ON_ONCE(cpu_has_apic && !disable_apic);
 }
 
-#ifdef CONFIG_X86_32
-static int noop_x86_32_numa_cpu_node(int cpu)
-{
-	/* we're always on node 0 */
-	return 0;
-}
-#endif
-
 struct apic apic_noop = {
 	.name				= "noop",
 	.probe				= noop_probe,
@@ -195,6 +187,5 @@ struct apic apic_noop = {
 
 #ifdef CONFIG_X86_32
 	.x86_32_early_logical_apicid	= noop_x86_32_early_logical_apicid,
-	.x86_32_numa_cpu_node		= noop_x86_32_numa_cpu_node,
 #endif
 };