cpu_x86: Probe host CPU for all MSR features

cpu_x86: Probe host CPU for all MSR features

The list of CPU features we probe from various MSR grew significantly
over time and the CPU map currently mentions 11 distinct MSR indexes.
But the code for directly probing host CPU features was still reading
only the original 0x10a index. Thus the CPU model in host capabilities
was missing a lot of features.

Instead of specifying a static list of indexes to read (which we would
forget to update in the future), let's just read all indexes found in
the CPU map.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>