hwmon: (w83791d) convert to use devm_i2c_new_dummy_device

And simplify the error handling.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20190903181256.13450-2-wsa+renesas@sang-engineering.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>