dt-bindings: dma: snps,dw-axi-dmac: add dma-coherent property

The Synopsys DesignWare AXI DMA Controller on Agilex5, the controller
operates on a cache-coherent AXI interface, where DMA transactions are
automatically kept coherent with the CPU caches. In previous generations
SoC (Stratix10 and Agilex) the interconnect was non-coherent, hence there
is no need for dma-coherent property to be presence. In Agilex 5, the
architecture has changed. It introduced a coherent interconnect that
supports cache-coherent DMA.

Signed-off-by: Khairul Anuar Romli <khairul.anuar.romli@altera.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Link: https://patch.msgid.link/20260131172856.29227-1-dinguyen@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>