dt-bindings: dma: dw-axi-dmac: extend the number of interrupts

dt-bindings: dma: dw-axi-dmac: extend the number of interrupts

The Canaan k210 apparently has a Sysnopsys Designware AXI DMA
controller, but according to the documentation & devicetree it has 6
interrupts rather than the standard one. Support the 6 interrupt
configuration by unconditionally extending the binding to a maximum of
8 per-channel interrupts thereby matching the number of possible
channels.

Link: https://canaan-creative.com/wp-content/uploads/2020/03/kendryte_standalone_programming_guide_20190311144158_en.pdf
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220705215213.1802496-4-mail@conchuod.ie
Signed-off-by: Vinod Koul <vkoul@kernel.org>