cpuidle: Fix kobject memory leaks in error paths

Commit c343bf1b ("cpuidle: Fix three reference count leaks")
fixes the cleanup of kobjects; however, it removes kfree() calls
altogether, leading to memory leaks.

Fix those and also defer the initialization of dev->kobj_dev until
after the error check, so that we do not end up with a dangling
pointer.

Fixes: c343bf1b ("cpuidle: Fix three reference count leaks")
Signed-off-by: Anel Orazgaliyeva <anelkz@amazon.de>
Suggested-by: Aman Priyadarshi <apeureka@amazon.de>
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>