dt-bindings: pl330: document the optional resets property

Add the optional resets property the pl330 dma node.
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/arm-pl330.txt

@@ -16,6 +16,9 @@ Optional properties:
   - dma-channels: contains the total number of DMA channels supported by the DMAC
   - dma-requests: contains the total number of DMA requests supported by the DMAC
   - arm,pl330-broken-no-flushp: quirk for avoiding to execute DMAFLUSHP
+  - resets: contains an entry for each entry in reset-names.
+	    See ../reset/reset.txt for details.
+  - reset-names: must contain at least "dma", and optional is "dma-ocp".
 
 Example: