hwmon: (ina3221) Add INA3221_CONFIG to volatile_table

The MSB (15th bit) of INA3221_CONFIG is a self-clear reset bit.
So this register should be added to the volatile_table of the
regmap_config. Otherwise, we will see this bit is sticky in the
regcache which might accidentally reset the chip when an actual
write happens to the register.

This might not be a severe bug for the current code line since
there's no second place touching the INA3221_CONFIG except the
reset routine in the probe().

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>