dt-bindings: PCI: fsl,imx6q-pcie: Add optional DMA interrupt

The i.MX8QM and i.MX8QXP/DXP have an additional interrupt for DMA.

Signed-off-by: Alexander Stein <[e-mail]>
Reviewed-by: Frank Li <[e-mail]>
Reviewed-by: Rob Herring (Arm) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Wilczyński <[e-mail]>

Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml

···
     maxItems: 5
 
   interrupts:
+    minItems: 1
     items:
       - description: builtin MSI controller.
+      - description: builtin DMA controller.
 
   interrupt-names:
+    minItems: 1
     items:
       - const: msi
+      - const: dma
 
   reset-gpio:
     description: Should specify the GPIO for controlling the PCI bus device