hwmon: (w83627ehf) add caseopen detection

Export caseopen alarm status into userspace for Winbond W83627*
and Nuvoton NCT677[56] chips and implement alarm clear attribute.
Second caseopen alarm on NCT6776 is also supported.

Signed-off-by: Dmitry Artamonow <mad_soft@inbox.ru>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>