hwmon: (ina2xx) bail-out from ina2xx_probe() in case of configuration errors

The return value of i2c_smbus_write_word_swapped() isn't checked in
ina2xx_probe(). This leads to devices being registered even if they cannot
be physically detected (e.g. device is not powered-up at boot-time).

Even after restoring power to such device, it is left unconfigured as the
configuration has never been actually written to the register.

Error out in case of write errors in probe and notify the user.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
[Guenter Roeck: Fixed multi-line comment style]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>