hwmon: (ds1621) Update zbits after conversion rate change

hwmon: (ds1621) Update zbits after conversion rate change

commit 39c627a084475e8a690a4a9e7601410ca173ddd2 upstream.

After the conversion rate is changed, the zbits are not updated,
but should be, since they are used later in the set_temp function.

Fixes: a50d9a4d9ad3 ("hwmon: (ds1621) Fix temperature rounding operations")
Reported-by: Murat Ilsever <murat.ilsever@gmail.com>
Signed-off-by: Robert Coulson <rob.coulson@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>