x86: merge hard/logical_smp_processor_id

The code is now the same between i386 and x86_64. We already
know what happens when it reaches this point: They go away
from the arch-specific headers, and suddenly appears in the common
header.

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