hwmon: (aspeed-pwm-tacho) Switch to using the new API kobj_to_dev()

fixed the following coccicheck:
drivers/hwmon/aspeed-pwm-tacho.c:634:60-61: WARNING opportunity for
kobj_to_dev()
drivers/hwmon/aspeed-pwm-tacho.c:623:60-61: WARNING opportunity for
kobj_to_dev()

Signed-off-by: Tian Tao <[e-mail]>
Acked-by: Joel Stanley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/aspeed-pwm-tacho.c

···
 static umode_t pwm_is_visible(struct kobject *kobj,
 			      struct attribute *a, int index)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct aspeed_pwm_tacho_data *priv = dev_get_drvdata(dev);
 
 	if (!priv->pwm_present[index])
···
 static umode_t fan_dev_is_visible(struct kobject *kobj,
 				  struct attribute *a, int index)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct aspeed_pwm_tacho_data *priv = dev_get_drvdata(dev);
 
 	if (!priv->fan_tach_present[index])