arm64: dts: imx8mm: Change SDMA1 ahb clock for imx8mm

Using SDMA1 with UART1 is causing a "Timeout waiting for CH0" error.
This patch changes to ahb clock from SDMA1_ROOT to AHB which
fixes the timeout error.

Fixes:  a05ea40 ("arm64: dts: imx: Add i.mx8mm dtsi support")
Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: aford173

arch/arm64/boot/dts/freescale/imx8mm.dtsi

@@ -740,7 +740,7 @@
 				reg = <0x30bd0000 0x10000>;
 				interrupts = <GIC_SPI 2 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clk IMX8MM_CLK_SDMA1_ROOT>,
-					 <&clk IMX8MM_CLK_SDMA1_ROOT>;
+					 <&clk IMX8MM_CLK_AHB>;
 				clock-names = "ipg", "ahb";
 				#dma-cells = <3>;
 				fsl,sdma-ram-script-name = "imx/sdma/sdma-imx7d.bin";