s390/topology: Remove CPU KOBJ_CHANGE uevents

s390 generates KOBJ_CHANGE uevents on CPUs whenever a topology update
occurs. These uevents currently have no users and they are also not
present on other architectures. As they are not necessary, remove
these extra uevents.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>