x86: make read_apic_id return final apicid

also remove GET_APIC_ID when read_apic_id is used.

need to apply after
	[PATCH] x86: mach_apicdef.h need to include before smp.h

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>