Unify IO APIC address specification

Some places still hardcoded the address instead of using IO_APIC_ADDR.

Change-Id: I3941c1ff62972ce56a5bc466eab7134f901773d3
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/677
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/iwave/iWRainbowG6/mptable.c

@@ -34,7 +34,7 @@ void *smp_write_config_table(void *v)
 	smp_write_processors(mc);
 	mptable_write_buses(mc, NULL, &isa_bus);
 
-	smp_write_ioapic(mc, 2, 0x20, 0xfec00000);
+	smp_write_ioapic(mc, 2, 0x20, IO_APIC_ADDR);
 	{
 		device_t dev;
 		struct resource *res;