staging: iio: meter: ade7854: Fix alignment for DMA safety

____cacheline_aligned is an insufficient guarantee for non-coherent DMA
on platforms with 128 byte cachelines above L1.  Switch to the updated
IIO_DMA_MINALIGN definition.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://lore.kernel.org/r/20220807151218.656881-4-jic23@kernel.org

drivers/staging/iio/meter/ade7854.h

@@ -162,7 +162,7 @@ struct ade7854_state {
 			 int bits);
 	int irq;
 	struct mutex buf_lock;
-	u8 tx[ADE7854_MAX_TX] ____cacheline_aligned;
+	u8 tx[ADE7854_MAX_TX] __aligned(IIO_DMA_MINALIGN);
 	u8 rx[ADE7854_MAX_RX];
 
 };