x86, cpufeature: If we disable CLFLUSH, we should disable CLFLUSHOPT

If we explicitly disable the use of CLFLUSH, we should disable the use
of CLFLUSHOPT as well.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-jtdv7btppr4jgzxm3sxx1e74@git.kernel.org