microcode: remove struct ucode_cpu_info

microcode: remove struct ucode_cpu_info

Remove the per-cpu cache field in struct ucode_cpu_info since it has
been replaced by a global cache. It would leads to only one field
remaining in ucode_cpu_info. Then, this struct is removed and the
remaining field (cpu signature) is stored in per-cpu area.

The cpu status notifier is also removed. It was used to free the "mc"
field to avoid memory leak.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>