This will let userland only try to use the new ring
when the appropriate kernel is present

v2: change the number to be consistent with upstream (Zhipeng)
Signed-off-by: Zhipeng Gong <zhipeng.gong@intel.com>
Reviewed--by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>