x86, AVX-512: AVX-512 Feature Detection

AVX-512 is an extention of AVX2. Its spec can be found at:
http://download-software.intel.com/sites/default/files/managed/71/2e/319433-017.pdf



This patch detects AVX-512 features by CPUID.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1392931491-33237-1-git-send-email-fenghua.yu@intel.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org> # hw enabling