driver core: remove make_class_name declaration

make_class_name has been removed since
commit 39aba963 ("driver core: remove CONFIG_SYSFS_DEPRECATED_V2
but keep it for block devices"), so remove it.
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20220909063337.1146151-1-cuigaosheng1@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/base.h

@@ -154,8 +154,6 @@ extern void driver_remove_groups(struct device_driver *drv,
 				 const struct attribute_group **groups);
 void device_driver_detach(struct device *dev);
 
-extern char *make_class_name(const char *name, struct kobject *kobj);
-
 extern int devres_release_all(struct device *dev);
 extern void device_block_probing(void);
 extern void device_unblock_probing(void);