iio: Fix bma180 dev-to-indio_dev conversion in suspend/resume

dev_to_iio_dev() is a false friend

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Cc: Oleksandr Kravchenko <o.v.kravchenko@globallogic.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>