hwmon: (ltc4215) Clear faults at startup

When power is applied to the ltc4215 chip it sometimes reports spurious
faults. The faults are not yet exposed via sysfs, however it may be useful
for userspace to read the fault register directly with the i2cget command.
Clear the fault register when the driver is installed so userspace doesn't
have to worry about spurious fault indications.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Jean Delvare <khali@linux-fr.org>