drm/nouveau: store a per-client channel list

Removes the need to disable IRQs to lookup channel struct on every pushbuf
ioctl, among others.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index b52e460..2bd8d6d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -139,7 +139,7 @@
 	}
 
 	if (req->channel_hint) {
-		chan = nouveau_channel_get(dev, file_priv, req->channel_hint);
+		chan = nouveau_channel_get(file_priv, req->channel_hint);
 		if (IS_ERR(chan))
 			return PTR_ERR(chan);
 	}
@@ -548,7 +548,7 @@
 	struct nouveau_fence *fence = NULL;
 	int i, j, ret = 0, do_reloc = 0;
 
-	chan = nouveau_channel_get(dev, file_priv, req->channel);
+	chan = nouveau_channel_get(file_priv, req->channel);
 	if (IS_ERR(chan))
 		return PTR_ERR(chan);