dmaengine: axi-dmac: Enable DMA_INTERLEAVE capability

Since device_prep_interleaved_dma() is already implemented, the
DMA_INTERLEAVE capability should be set.

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>