x86: apic_32.c should use __cpuinit section

All callers are __init or __cpuinit so there is no need
to hold this code without CPU_HOTPLUG being set.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>