[media] davinci: vpfe: fix return value check in vpfe_enable_clock()

In case of error, the function clk_get() returns ERR_PTR()
and never returns NULL. The NULL test in the return value
check should be replaced with IS_ERR().

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Reviewed-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/media/davinci_vpfe/vpfe_mc_capture.c

@@ -243,7 +243,7 @@ static int vpfe_enable_clock(struct vpfe_device *vpfe_dev)
 
 		vpfe_dev->clks[i] =
 				clk_get(vpfe_dev->pdev, vpfe_cfg->clocks[i]);
-		if (vpfe_dev->clks[i] == NULL) {
+		if (IS_ERR(vpfe_dev->clks[i])) {
 			v4l2_err(vpfe_dev->pdev->driver,
 				"Failed to get clock %s\n",
 				vpfe_cfg->clocks[i]);
@@ -264,7 +264,7 @@ static int vpfe_enable_clock(struct vpfe_device *vpfe_dev)
 	return 0;
 out:
 	for (i = 0; i < vpfe_cfg->num_clocks; i++)
-		if (vpfe_dev->clks[i]) {
+		if (!IS_ERR(vpfe_dev->clks[i])) {
 			clk_disable_unprepare(vpfe_dev->clks[i]);
 			clk_put(vpfe_dev->clks[i]);
 		}