dt-bindings: dma: fsl-edma: fix ls1028a-edma compatible

The bootloader will fix up the IOMMU entries only on nodes with the
compatible "fsl,vf610-edma". Thus make this compatible string mandatory
for the ls1028a-edma.

While at it, fix the "fsl,fsl," typo.
Signed-off-by: Michael Walle <michael@walle.cc>
Fixes: d8c1bdb5 ("dt-bindings: dma: fsl-edma: add new fsl,fsl,ls1028a-edma")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

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

@@ -10,7 +10,8 @@ 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
+	- "fsl,ls1028a-edma" followed by "fsl,vf610-edma" for eDMA used on the
+	  LS1028A 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