If clflushopt is available on the system, use it instead of clflush in
drm_clflush_virt_range.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Link: http://lkml.kernel.org/r/1393441612-19729-5-git-send-email-ross.zwisler@linux.intel.comSigned-off-by: H. Peter Anvin <hpa@linux.intel.com>