x86: refactor ->setup_portio_remap() subarch methods

Only NUMAQ has a real ->setup_portio_remap() method, the other
subarchitectures define it but keep it empty.

So mark the vector as NULL, extend the generic code to handle
NULL -setup_portio_remap() entries and remove all the empty
handlers.

Also move the NUMAQ method from the header file into the
 apic driver .c file.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 812bf39..0e7d26c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1170,7 +1170,8 @@
 
 	map_cpu_to_logical_apicid();
 
-	setup_portio_remap();
+	if (apic->setup_portio_remap)
+		apic->setup_portio_remap();
 
 	smpboot_setup_io_apic();
 	/*