iio: adc: ad_sigma_delta: use sizeof() in ALIGN()

iio: adc: ad_sigma_delta: use sizeof() in ALIGN()

Use sizeof() instead of hardcoding the size of the timestamp in the
ALIGN() macro. This makes it a bit more obvious what the intention of
the code is.

Suggested-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://patch.msgid.link/20250701-iio-adc-ad7173-add-spi-offload-support-v3-4-42abb83e3dac@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>