Document the new Atom series (Tunnel Creek and Medfield) as being
supported, and list TjMax for the Atom E600 series.

Also enable the Atom tjmax heuristic for these Atom CPU models.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Reviewed-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: Alexander Stein <alexander.stein@systec-electronic.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "R, Durgadoss" <durgadoss.r@intel.com>