docs: filesystems: replace to_dev() with kobj_to_dev()

Commit a4232963 ("driver-core: Move kobj_to_dev from genhd.h to device.h")
introduced kobj_to_dev() function.
Signed-off-by: Denis Efremov <efremov@linux.com>
Link: https://lore.kernel.org/r/20200830144135.6956-1-efremov@linux.comSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/sysfs.rst

@@ -172,14 +172,13 @@ calls the associated methods.
 
 To illustrate::
 
-    #define to_dev(obj) container_of(obj, struct device, kobj)
     #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
 
     static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
 				char *buf)
     {
 	    struct device_attribute *dev_attr = to_dev_attr(attr);
-	    struct device *dev = to_dev(kobj);
+	    struct device *dev = kobj_to_dev(kobj);
 	    ssize_t ret = -EIO;
 
 	    if (dev_attr->show)

Documentation/translations/zh_CN/filesystems/sysfs.txt

@@ -154,14 +154,13 @@ sysfs 会为这个类型调用适当的方法。当一个文件被读写时，
 
 示例:
 
-#define to_dev(obj) container_of(obj, struct device, kobj)
 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
 
 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
                              char *buf)
 {
         struct device_attribute *dev_attr = to_dev_attr(attr);
-        struct device *dev = to_dev(kobj);
+        struct device *dev = kobj_to_dev(kobj);
         ssize_t ret = -EIO;
 
         if (dev_attr->show)