x86, cpu: Add xsaveopt cpufeature

Add cpu feature bit support for the XSAVEOPT instruction.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20100719230205.523204988@sbs-t61.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>