Add __init to probe_bigsmp.  All callers are __init and data being examined
is __initdata.

Resolves MODPOST warning similar to:

WARNING: vmlinux - Section mismatch: reference to .init.data: from .text between 'probe_bigsmp' (at offset 0xc0401e56) and 'init_apic_ldr'
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>