dt-bindings: dma: snps,dw-axi-dmac: Document optional reset

"make dtbs_check":

    Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml
    arch/riscv/boot/dts/canaan/sipeed_maix_bit.dt.yaml: dma-controller@50000000: 'resets' does not match any of the regexes: 'pinctrl-[0-9]+'
	    From schema: Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml

The Synopsys DesignWare AXI DMA Controller on the Canaan K210 SoC
exposes its reset signal.

Signed-off-by: Geert Uytterhoeven <[email protected]>
Acked-by: Rob Herring <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: geertu

Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml

@@ -53,6 +53,9 @@ properties:
     minimum: 1
     maximum: 8
 
+  resets:
+    maxItems: 1
+
   snps,dma-masters:
     description: |
       Number of AXI masters supported by the hardware.