hwmon: Remove ads1015 driver

A driver for ADS1015 with more functionality is available in the iio
subsystem.

Remove the hwmon driver as duplicate. If the chip is used for hardware
monitoring, the iio->hwmon bridge should be used.

Cc: Dirk Eibach <eibach@gdsys.de>
Link: https://lore.kernel.org/r/1562004758-13025-1-git-send-email-linux@roeck-us.net


Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>