input: touchscreen: mxs-lradc: use correct error check

[Pan Bian]

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@xxxxxxx>
---
 drivers/input/touchscreen/mxs-lradc-ts.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/touchscreen/mxs-lradc-ts.c b/drivers/input/touchscreen/mxs-lradc-ts.c
index 58c016c..9bcc98c6 100644
--- a/drivers/input/touchscreen/mxs-lradc-ts.c
+++ b/drivers/input/touchscreen/mxs-lradc-ts.c
@@ -631,8 +631,8 @@ static int mxs_lradc_ts_probe(struct platform_device *pdev)
 
 	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	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);
-- 
1.9.1