Input: mxs-lradc - use correct error check

Function devm_ioremap() will return a NULL pointer on failure. However,
in function mxs_lradc_ts_probe(), its return value is checked with
IS_ERR(), which cannot detect the exceptional case.
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/mxs-lradc-ts.c

@@ -633,8 +633,8 @@ static int mxs_lradc_ts_probe(struct platform_device *pdev)
 	if (!iores)
 		return -EINVAL;
 	ts->base = devm_ioremap(dev, iores->start, resource_size(iores));
-	if (IS_ERR(ts->base))
-		return PTR_ERR(ts->base);
+	if (!ts->base)
+		return -ENOMEM;
 
 	ret = of_property_read_u32(node, "fsl,lradc-touchscreen-wires",
 				   &ts_wires);