hwmon: (coretemp) Properly label the sensors

Don't assume that CPU entry number and core ID always match. It
worked in the simple cases (single CPU, no HT) but fails on
multi-CPU systems.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Huaxu Wan <huaxu.wan@intel.com>
Cc: stable@kernel.org