x86, acpi: Map hotadded cpu to correct node.

When hotadd new cpu to system, if its affinitive node is online,
should map the cpu to its own node.  Otherwise, let kernel select one
online node for the new cpu later.

Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
LKML-Reference: <4B6AAA39.6000300@linux.intel.com>
Tested-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>