hwmon: (adt7410) Add device table entry for the adt7420

The adt7420 is software compatible to the adt7410.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>