dmaengine: xilinx: xdma: Support cyclic transfers

dmaengine: xilinx: xdma: Support cyclic transfers

In order to use this dmaengine with sound devices, let's add cyclic
transfers support. Most of the code is reused from the existing
scatter-gather implementation, only the final linking between
descriptors, the control fields (to trigger interrupts more often) and
the interrupt handling are really different.

This controller supports up to 32 adjacent descriptors, we assume this
is way more than enough for the purpose of cyclic transfers and limit to
32 the number of cycled descriptors. This way, we simplify a lot the
overall handling of the descriptors.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20231005160237.2804238-4-miquel.raynal@bootlin.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>