i386: Add new CPU model Cooperlake

i386: Add new CPU model Cooperlake

Cooper Lake is intel's successor to Cascade Lake, the new
CPU model inherits features from Cascadelake-Server, while
add one platform associated new feature: AVX512_BF16. Meanwhile,
add STIBP for speculative execution.

Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Tao Xu <tao3.xu@intel.com>
Message-Id: <1571729728-23284-4-git-send-email-cathy.zhang@intel.com>
Reviewed-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>