[ACPI] correct earlier SMP deep C-states on HT patch

http://bugzilla.kernel.org/show_bug.cgi?id=5165

Change polarity of test for PLVL2_UP flag.
Skip promotion/demotion code when not needed.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>