dmaengine: idxd: return 0 if wq already enabled instead of error

commit 3a5e5ffd0d28c0c9b71f047668baca77723b6875 Intel-BKC.

If wq is already enabled and idxd_wq_enable() is called, return 0 instead
of error since it's not a real error.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Chen Zhuo <sagazchen@tencent.com>
Signed-off-by: Xinghui Li <korantli@tencent.com>

drivers/dma/idxd/device.c

@@ -248,7 +248,7 @@ int idxd_wq_enable(struct idxd_wq *wq, u32 *status)
 
 	if (wq->state == IDXD_WQ_ENABLED) {
 		dev_dbg(dev, "WQ %d already enabled\n", wq->id);
-		return -ENXIO;
+		return 0;
 	}
 
 	idxd_cmd_exec(idxd, IDXD_CMD_ENABLE_WQ, wq->id, &stat);