ACPI / idle: override and update c-state latency when not conformance with s0ix

Generally the C-state latency get by _CST method but some OEM platform set the
C2 latency no less than C3's and that will block the core enter PC6. This issue
can be workaround by override and update C-state latency.

Change-Id: I81f6e634c6881f69311d21afdad74bb78807c534
Signed-off-by: Prike.Liang <Prike.Liang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>