x86: Implement the default x86_32_early_logical_apicid()

Implement x86_32_early_logical_apicid() for the default apic
flat routing.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: eric.dumazet@gmail.com
Cc: yinghai@kernel.org
Cc: brgerst@gmail.com
Cc: gorcunov@gmail.com
Cc: penberg@kernel.org
Cc: shaohui.zheng@intel.com
Cc: rientjes@google.com
LKML-Reference: <1295789862-25482-9-git-send-email-tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>