x86: move equal types to common file

move definitions that are now equal in type from
smpboot_{32,64}.c to smpboot.c

cpu_callin_map is put temporarily in smp_64.h (already
exists in smp_32.h), and will soon be merged.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>