MX31 clkdev support

This patch adds clkdev support for i.MX31. This is done in a
similar way done previously for i.MX27

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/drivers/dma/ipu/ipu_idmac.c b/drivers/dma/ipu/ipu_idmac.c
index ae50a9d..da781d1 100644
--- a/drivers/dma/ipu/ipu_idmac.c
+++ b/drivers/dma/ipu/ipu_idmac.c
@@ -1649,7 +1649,7 @@
 	}
 
 	/* Get IPU clock */
-	ipu_data.ipu_clk = clk_get(&pdev->dev, "ipu_clk");
+	ipu_data.ipu_clk = clk_get(&pdev->dev, NULL);
 	if (IS_ERR(ipu_data.ipu_clk)) {
 		ret = PTR_ERR(ipu_data.ipu_clk);
 		goto err_clk_get;