hwmon: (coretemp) Add maximum cooling temperature readout

Following patch will add reporting of maximum temperature, at which all fans
should spin full speed. It may be non-physical temperature on Desktop/Server CPUs.

Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>