x86: enable_update_mptable should be a macro

instead of declaring one variant as an inline function...
because other case is a variable

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4A13B344.7030307@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>