dmaengine: axi-dmac: Add support for interleaved cyclic transfers

The DMAC HDL core supports interleaved & cyclic transfers.
An example use-case for this mode is when the controller is used as a
video DMA.

This change sets the `cyclic` field to true, so that when the IRQ comes and
the `axi_dmac_transfer_done()` callback is called (from the interrupt
handler) the proper `vchan_cyclic_callback()` is called. This way the
DMAEngine framework will process data correctly for interleaved + cyclic
transfers.

This doesn't fix anything. It's an enhancement to the driver.
Signed-off-by: Dragos Bogdan <dragos.bogdan@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/dma-axi-dmac.c

@@ -562,6 +562,9 @@ static struct dma_async_tx_descriptor *axi_dmac_prep_interleaved(
 		desc->sg[0].y_len = 1;
 	}
 
+	if (flags & DMA_CYCLIC)
+		desc->cyclic = true;
+
 	return vchan_tx_prep(&chan->vchan, &desc->vdesc, flags);
 }