s390x/mmu_helper: avoid setting the storage key if nothing changed

Avoid setting the key if nothing changed.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210903155514.44772-9-david@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
1 file changed