hwmon: (it87) Add support for IT8786E

IT8786E is mostly compatible with IT8771 / IT8772.
Parameters determined by testing various combinations.

Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Thomas Lorblanches <zlika_ese@hotmail.com>
[Guenter Roeck: merged from github, addressed review comments]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>