hwmon: (i5k_amb) remove redundant assignment to variable res

hwmon: (i5k_amb) remove redundant assignment to variable res

The variable res is being initialized with a value that is
never read and it is being updated later with a new value. The
initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20200610123638.1133428-1-colin.king@canonical.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>