Input: ili210x - fix permissions on "calibrate" attribute

"calibrate" attribute does not provide "show" methods and thus we should
not mark it as readable.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/drivers/input/touchscreen/ili210x.c b/drivers/input/touchscreen/ili210x.c
index ddf694b..fe4848b 100644
--- a/drivers/input/touchscreen/ili210x.c
+++ b/drivers/input/touchscreen/ili210x.c
@@ -169,7 +169,7 @@
 
 	return count;
 }
-static DEVICE_ATTR(calibrate, 0644, NULL, ili210x_calibrate);
+static DEVICE_ATTR(calibrate, S_IWUSR, NULL, ili210x_calibrate);
 
 static struct attribute *ili210x_attributes[] = {
 	&dev_attr_calibrate.attr,