hwmon: (coretemp) Add support for thermal threshold attributes

hwmon: (coretemp) Add support for thermal threshold attributes

Add support for T0 and T1 temperature thresholds using the new sysfs ABI
attributes tempX_thresholdY and tempX_thresholdY_triggered.

This patch is based on commit c814a4c7c4aad795835583344353963a0a673eb0, which
was reverted. For details on the threshold registers, see IA Manual vol 3A,
which can be downloaded from here:
        http://download.intel.com/design/processor/manuals/253668.pdf

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>