Add package level thermal and power limit feature support.

The two MSRs and features are new starting with Intel's Sandy Bridge processor.

Please check Intel 64 and IA-32 Architectures SDMV Vol 3A 14.5.6 Power Limit
Notification and 14.6 Package Level Thermal Management.

This patch also fixes a bug which defines reverse THERM_INT_LOW_ENABLE bit and
THERM_INT_HIGH_ENABLE bit.

[ hpa: fixed up against current tip:x86/cpu ]
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
LKML-Reference: <1280448826-12004-2-git-send-email-fenghua.yu@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>