debugfs: Correct the 'debugfs_create_str' docs

The documentation of the 'debugfs_create_str' says that the function
returns a pointer to a dentry created, or an ERR_PTR in case of error.
Actually, this is not true: this function doesn't return anything at all.
Correct the documentation correspondingly.
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230514172353.52878-1-ivan.orlov0322@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/debugfs/file.c

@@ -940,15 +940,6 @@ static const struct file_operations fops_str_wo = {
  * This function creates a file in debugfs with the given name that
  * contains the value of the variable @value.  If the @mode variable is so
  * set, it can be read from, and written to.
- *
- * This function will return a pointer to a dentry if it succeeds.  This
- * pointer must be passed to the debugfs_remove() function when the file is
- * to be removed (no automatic cleanup happens if your module is unloaded,
- * you are responsible here.)  If an error occurs, ERR_PTR(-ERROR) will be
- * returned.
- *
- * If debugfs is not enabled in the kernel, the value ERR_PTR(-ENODEV) will
- * be returned.
  */
 void debugfs_create_str(const char *name, umode_t mode,
 			struct dentry *parent, char **value)