hwmon: (w83627ehf) Use 16 bit fan count registers if supported

Some of the chips supported by this driver have 13 bit or 16 bit fan count
registers. This patch improves support for those registers, specifically for
NCT6775F. With the changes in this patch, fan speed is reported correctly even
if the fan divider is set to a low value, which results in a fan speed reading
above 0xff.

With this patch, the width of fan count registers is no longer used to determine
if the chip has fan divider register(s) or not. A dedicated flag is used instead
to determine if this is the case.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Ian Dobson <i.dobson@planet-ian.com>