drivers/regulator/virtual: avoid world-writable sysfs files.

In line with practice for module parameters, we're adding a build-time
check that sysfs files aren't world-writable.

Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/regulator/virtual.c

@@ -266,11 +266,11 @@ static ssize_t set_mode(struct device *dev, struct device_attribute *attr,
 	return count;
 }
 
-static DEVICE_ATTR(min_microvolts, 0666, show_min_uV, set_min_uV);
-static DEVICE_ATTR(max_microvolts, 0666, show_max_uV, set_max_uV);
-static DEVICE_ATTR(min_microamps, 0666, show_min_uA, set_min_uA);
-static DEVICE_ATTR(max_microamps, 0666, show_max_uA, set_max_uA);
-static DEVICE_ATTR(mode, 0666, show_mode, set_mode);
+static DEVICE_ATTR(min_microvolts, 0664, show_min_uV, set_min_uV);
+static DEVICE_ATTR(max_microvolts, 0664, show_max_uV, set_max_uV);
+static DEVICE_ATTR(min_microamps, 0664, show_min_uA, set_min_uA);
+static DEVICE_ATTR(max_microamps, 0664, show_max_uA, set_max_uA);
+static DEVICE_ATTR(mode, 0664, show_mode, set_mode);
 
 static struct attribute *regulator_virtual_attributes[] = {
 	&dev_attr_min_microvolts.attr,