dt-bindings: dma: fsl-edma: add new fsl,fsl,ls1028a-edma

QORIQ LS1028A soc used fsl,vf610-edma, but it has a little bit different
from others, so add new compatible to distinguish them.
Signed-off-by: Peng Ma <peng.ma@nxp.com>
Link: https://lore.kernel.org/r/20191212033714.4090-3-peng.ma@nxp.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/fsl-edma.txt

@@ -10,6 +10,7 @@ Required properties:
 - compatible :
 	- "fsl,vf610-edma" for eDMA used similar to that on Vybrid vf610 SoC
 	- "fsl,imx7ulp-edma" for eDMA2 used similar to that on i.mx7ulp
+	- "fsl,fsl,ls1028a-edma" for eDMA used similar to that on Vybrid vf610 SoC
 - reg : Specifies base physical address(s) and size of the eDMA registers.
 	The 1st region is eDMA control register's address and size.
 	The 2nd and the 3rd regions are programmable channel multiplexing