MIPS: vpe-mt: fix possible memory leak while module exiting

Afer commit 1fa5ae85 ("driver core: get rid of struct device's
bus_id string array"), the name of device is allocated dynamically,
it need be freed when module exiting, call put_device() to give up
reference, so that it can be freed in kobject_cleanup() when the
refcount hit to 0. The vpe_device is static, so remove kfree() from
vpe_device_release().

Fixes: 1fa5ae85 ("driver core: get rid of struct device's bus_id string array")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/kernel/vpe-mt.c

@@ -313,7 +313,6 @@ ATTRIBUTE_GROUPS(vpe);
 
 static void vpe_device_release(struct device *cd)
 {
-	kfree(cd);
 }
 
 static struct class vpe_class = {
@@ -497,6 +496,7 @@ int __init vpe_module_init(void)
 	device_del(&vpe_device);
 
 out_class:
+	put_device(&vpe_device);
 	class_unregister(&vpe_class);
 
 out_chrdev:
@@ -509,7 +509,7 @@ void __exit vpe_module_exit(void)
 {
 	struct vpe *v, *n;
 
-	device_del(&vpe_device);
+	device_unregister(&vpe_device);
 	class_unregister(&vpe_class);
 	unregister_chrdev(major, VPE_MODULE_NAME);