x86, cpu: Split addon_cpuid_features.c

addon_cpuid_features.c contains exactly two almost completely
unrelated functions, plus has a long and very generic name.  Split it
into two files, scattered.c for the scattered feature flags, and
topology.c for the topology information.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <tip-*@git.kernel.org>