ARM: dts: add dm816x missing spi DT dma handles

Add the missing SPI controller DMA handler in the dm816x DT
node, only properties for the two channels on four were present.

Cc: Brian Hutchinson <b.hutchman@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Author: superna9999

arch/arm/boot/dts/dm816x.dtsi

@@ -280,8 +280,11 @@
 			ti,spi-num-cs = <4>;
 			ti,hwmods = "mcspi1";
 			dmas = <&edma 16 &edma 17
-				&edma 18 &edma 19>;
-			dma-names = "tx0", "rx0", "tx1", "rx1";
+				&edma 18 &edma 19
+				&edma 20 &edma 21
+				&edma 22 &edma 23>;
+			dma-names = "tx0", "rx0", "tx1", "rx1",
+				    "tx2", "rx2", "tx3", "rx3";
 		};
 
 		mmc1: mmc@48060000 {