make sure we wait for rings to become idle once they are
disabled. In case of timeout print an error message
Signed-off-by: NNaresh Kumar Kachhi <naresh.kumar.kachhi@intel.com>
[danvet: Frob patch as suggested by Chris.]
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>