iio: hi8435: Drop hi8435_remove() by using devres for remaining elements

Convert the remainder of hi8435_probe() to use devres and get rid of
hi8435_remove().

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-iio@vger.kernel.org
Cc: Chris Healy <cphealy@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>