hwmon: Switch to using the new API kobj_to_dev()

fixed the following coccicheck:
./drivers/hwmon/hwmon.c:82:60-61: WARNING opportunity for kobj_to_dev()
Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: NYang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1614071667-5665-1-git-send-email-yang.lee@linux.alibaba.comSigned-off-by: NGuenter Roeck <linux@roeck-us.net>

drivers/hwmon/hwmon.c

@@ -79,7 +79,7 @@ static struct attribute *hwmon_dev_attrs[] = {
 static umode_t hwmon_dev_name_is_visible(struct kobject *kobj,
 					 struct attribute *attr, int n)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 
 	if (to_hwmon_device(dev)->name == NULL)
 		return 0;