x86, mce: Fix MSR_IA32_MCI_CTL2 CMCI threshold setup

It is reported that CMCI is not raised when number of corrected error
reaches preset threshold. After inspection, it is found that
MSR_IA32_MCI_CTL2 threshold field is not setup properly. This patch
fixed it.

Value of MCI_CTL2_CMCI_THRESHOLD_MASK is fixed according to x86_64
Software Developer's Manual too.

Reported-by: Shaohui Zheng <shaohui.zheng@intel.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
LKML-Reference: <1275977350.3444.660.camel@yhuang-dev.sh.intel.com>
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>