arm64: dts: imx8mq: Add UART DMA support

UART ports have DMA capability. Describe the UART DMA properties.
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq.dtsi

@@ -940,6 +940,8 @@ uart1: serial@30860000 {
 				clocks = <&clk IMX8MQ_CLK_UART1_ROOT>,
 				         <&clk IMX8MQ_CLK_UART1_ROOT>;
 				clock-names = "ipg", "per";
+				dmas = <&sdma1 22 4 0>, <&sdma1 23 4 0>;
+				dma-names = "rx", "tx";
 				status = "disabled";
 			};
 
@@ -951,6 +953,8 @@ uart3: serial@30880000 {
 				clocks = <&clk IMX8MQ_CLK_UART3_ROOT>,
 				         <&clk IMX8MQ_CLK_UART3_ROOT>;
 				clock-names = "ipg", "per";
+				dmas = <&sdma1 26 4 0>, <&sdma1 27 4 0>;
+				dma-names = "rx", "tx";
 				status = "disabled";
 			};
 
@@ -962,6 +966,8 @@ uart2: serial@30890000 {
 				clocks = <&clk IMX8MQ_CLK_UART2_ROOT>,
 				         <&clk IMX8MQ_CLK_UART2_ROOT>;
 				clock-names = "ipg", "per";
+				dmas = <&sdma1 24 4 0>, <&sdma1 25 4 0>;
+				dma-names = "rx", "tx";
 				status = "disabled";
 			};
 
@@ -1157,6 +1163,8 @@ uart4: serial@30a60000 {
 				clocks = <&clk IMX8MQ_CLK_UART4_ROOT>,
 				         <&clk IMX8MQ_CLK_UART4_ROOT>;
 				clock-names = "ipg", "per";
+				dmas = <&sdma1 28 4 0>, <&sdma1 29 4 0>;
+				dma-names = "rx", "tx";
 				status = "disabled";
 			};