pwm: renesas-tpu: fix return value check in tpu_probe()

In case of error, the function devm_ioremap_resource() returns ERR_PTR()
and never returns NULL. The NULL test in the return value check should
be replaced with IS_ERR().
Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
Reviewed-by: NAxel Lin <axel.lin@ingics.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-renesas-tpu.c

@@ -410,10 +410,8 @@ static int tpu_probe(struct platform_device *pdev)
 	}
 
 	tpu->base = devm_ioremap_resource(&pdev->dev, res);
-	if (tpu->base == NULL) {
-		dev_err(&pdev->dev, "failed to remap I/O memory\n");
-		return -ENXIO;
-	}
+	if (IS_ERR(tpu->base))
+		return PTR_ERR(tpu->base);
 
 	tpu->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(tpu->clk)) {