iio: imu: inv_icm42600: reorganize DMA aligned buffers in structure

iio: imu: inv_icm42600: reorganize DMA aligned buffers in structure

Move all DMA aligned buffers together at the end of the structure.

1. Timestamp anynomous structure is not used with DMA so it doesn't
belong after __aligned(IIO_DMA_MINALIGN).
2. struct inv_icm42600_fifo contains it's own __aligned(IIO_DMA_MINALIGN)
within it at the end so it should not be after __aligned(IIO_DMA_MINALIGN)
in the outer struct either.
3. Normally 1 would have been considered a bug, but because of the extra
alignment from 2, it actually was OK, but we shouldn't be relying on such
quirks.

Signed-off-by: Jean-Baptiste Maneyrol <jean-baptiste.maneyrol@tdk.com>
Link: https://patch.msgid.link/20250630-losd-3-inv-icm42600-add-wom-support-v6-1-5bb0c84800d9@tdk.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>