kobject: convert /sys/hypervisor to use kobject_create

We don't need a kset here, a simple kobject will do just fine, so
dynamically create the kobject and use it.

We also rename hypervisor_subsys to hypervisor_kset to catch all users
of the variable.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index bd741e8..f2483f6 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -196,8 +196,8 @@
 
 /* The global /sys/kernel/ kset for people to chain off of */
 extern struct kset *kernel_kset;
-/* The global /sys/hypervisor/ subsystem  */
-extern struct kset hypervisor_subsys;
+/* The global /sys/hypervisor/ kobject for people to chain off of */
+extern struct kobject *hypervisor_kobj;
 
 extern int __must_check subsystem_register(struct kset *);
 extern void subsystem_unregister(struct kset *);