hwmon: (f75375s) Use standard sysfs attribute names

The driver uses non-standard sysfs attribute names for maximum and target fan
speeds, even though standard attibute names for the same values do exist.
Replace non-standard attribute names with standard attribute names.

Cc: Riku Voipio <riku.voipio@iki.fi>
Reviewed-by: Bjoern Gerhart <oss@extracloud.de>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>