clk: x86: pmc-atom: Checking for IS_ERR() instead of NULL

clkdev_hw_create() returns NULLs on error, it doesn't return error
pointers.

Fixes: 41ee7caf59e1 ("clk: x86: add "mclk" alias for Baytrail/Cherrytrail")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/x86/clk-pmc-atom.c

@@ -339,8 +339,8 @@ static int plt_clk_probe(struct platform_device *pdev)
 		}
 	}
 	data->mclk_lookup = clkdev_hw_create(&data->clks[3]->hw, "mclk", NULL);
-	if (IS_ERR(data->mclk_lookup)) {
-		err = PTR_ERR(data->mclk_lookup);
+	if (!data->mclk_lookup) {
+		err = -ENOMEM;
 		goto err_unreg_clk_plt;
 	}