kobject: convert kernel_kset to be a kobject

kernel_kset does not need to be a kset, but a much simpler kobject now
that we have kobj_attributes.

We also rename kernel_kset to kernel_kobj to catch all users of this
symbol with a build error instead of an easy-to-ignore build warning.

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

diff --git a/kernel/user.c b/kernel/user.c
index 5a106f3..7f17e6e 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -201,7 +201,7 @@
  */
 int __init uids_sysfs_init(void)
 {
-	uids_kset = kset_create_and_add("uids", NULL, &kernel_kset->kobj);
+	uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
 	if (!uids_kset)
 		return -ENOMEM;