iio: adis16400: Set timestamp as the last element in chan_spec

iio: adis16400: Set timestamp as the last element in chan_spec

commit c76782d151dab7ecfdcdf9a01561c2d61d9b490f upstream.

This is necessary since timestamp is calculated as the last element
in iio_compute_scan_bytes().

Without this fix any userspace code reading the layout of the buffer via
sysfs will incorrectly interpret the data leading some nasty corruption.

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>