x86: Fix build failure on X86_UP_APIC

Commit 4c321ff8 (x86: Replace cpu_2_logical_apicid[] with early
percpu variable) and following changes introduced and used
x86_cpu_to_logical_apicid percpu variable.  It was declared and
defined inside CONFIG_SMP && CONFIG_X86_32 but if
CONFIG_X86_UP_APIC is set UP configuration makes use of it and
build fails.

Fix it by declaring and defining it inside CONFIG_X86_LOCAL_APIC
&& CONFIG_X86_32.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
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: <20110128162248.GA25746@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>