iio: adc: ti-ads7950: use iio_push_to_buffers_with_ts_unaligned()

iio: adc: ti-ads7950: use iio_push_to_buffers_with_ts_unaligned()

Use iio_push_to_buffers_with_ts_unaligned() to avoid unaligned access
when writing the timestamp in the rx_buf.

The previous implementation would have been fine on architectures that
support 4-byte alignment of 64-bit integers but could cause issues on
architectures that require 8-byte alignment.

Fixes: 902c4b2446d4 ("iio: adc: New driver for TI ADS7950 chips")
Signed-off-by: David Lechner <dlechner@baylibre.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>