x86: consistent about warm_reset_vector for UN_NON_UNIQUE_APIC

Impact: cleanup

didn't set it for UV_NON_UNIQUE_APIC, so don't restore it

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49D6A6B9.6060501@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>