iio: temp: maxim-thermocouple: Fix potential lack of DMA safe buffer.

iio: temp: maxim-thermocouple: Fix potential lack of DMA safe buffer.

The trick of using __aligned(IIO_DMA_MINALIGN) ensures that there is
no overlap between buffers used for DMA and those used for driver
state storage that are before the marking. It doesn't ensure
anything above state variables found after the marking. Hence
move this particular bit of state earlier in the structure.

Fixes: 10897f34309b ("iio: temp: maxim_thermocouple: Fix alignment for DMA safety")
Reviewed-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250413103443.2420727-14-jic23@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>