x86/cpu: Enable MOVDIR64B cpu feature

x86/cpu: Enable MOVDIR64B cpu feature

MOVDIR64B moves 64-bytes as direct-store with 64-bytes write atomicity.
Direct store is implemented by using write combining (WC) for writing
data directly into memory without caching the data.

The bit definition:
CPUID.(EAX=7,ECX=0):ECX[bit 28] MOVDIR64B

The release document ref below link:
https://software.intel.com/sites/default/files/managed/c5/15/\
architecture-instruction-set-extensions-programming-reference.pdf

Cc: Xu Tao <tao3.xu@intel.com>
Signed-off-by: Liu Jingqi <jingqi.liu@intel.com>
Message-Id: <1541488407-17045-3-git-send-email-jingqi.liu@intel.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>