drm/nouveau: add more fine-grained locking to channel list + structures

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nv10_fifo.c b/drivers/gpu/drm/nouveau/nv10_fifo.c
index f1b03ad..39328fc 100644
--- a/drivers/gpu/drm/nouveau/nv10_fifo.c
+++ b/drivers/gpu/drm/nouveau/nv10_fifo.c
@@ -241,7 +241,7 @@
 	pfifo->reassign(dev, true);
 
 	for (i = 0; i < dev_priv->engine.fifo.channels; i++) {
-		if (dev_priv->fifos[i]) {
+		if (dev_priv->channels.ptr[i]) {
 			uint32_t mode = nv_rd32(dev, NV04_PFIFO_MODE);
 			nv_wr32(dev, NV04_PFIFO_MODE, mode | (1 << i));
 		}