spi: lpspi: add dmas property

The LPSPI has dma capability, so add dma property.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220812073452.45763-1-peng.fan@oss.nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml

@@ -39,6 +39,16 @@ properties:
       - const: per
       - const: ipg
 
+  dmas:
+    items:
+      - description: TX DMA Channel
+      - description: RX DMA Channel
+
+  dma-names:
+    items:
+      - const: tx
+      - const: rx
+
   fsl,spi-only-use-cs1-sel:
     description:
       spi common code does not support use of CS signals discontinuously.