Tearing down the ring buffers across resume is overkill, risks
unnecessary failure and increases fragmentation.

After failure, since the device is still active we may end up trying to
write into the dangling iomapping and trigger an oops.

v2: stop_ringbuffers() was meant to call stop(ring) not
cleanup(ring) during resume!
Reported-by: NJae-hyeon Park <jhyeon@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=72351
References: https://bugs.freedesktop.org/show_bug.cgi?id=76554Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NOscar Mateo <oscar.mateo@intel.com>
[danvet: s/ring->obj == NULL/!intel_ring_initialized(ring)/ as
suggested by Oscar.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>