hwmon: (w83781d) convert to i2c_new_dummy_device

Move from i2c_new_dummy() to i2c_new_dummy_device(), so we now get an
ERRPTR which we use in error handling.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20190722172611.3797-4-wsa+renesas@sang-engineering.com


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