arm64: dts: layerscape: rename aux_bus to aux-bus

Rename aux_bus to aux-bus to fix below CHECK_DTBS warning.
arch/arm64/boot/dts/freescale/fsl-ls1043a-rdb.dtb:
    aux_bus: $nodename:0: 'aux_bus' does not match '^([a-z][a-z0-9\\-]+-bus|bus|localbus|soc|axi|ahb|apb)(@.+)?$'
        from schema $id: http://devicetree.org/schemas/simple-bus.yam

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/fsl-ls1043a.dtsi

@@ -805,7 +805,7 @@
 					    QORIQ_CLK_PLL_DIV(1)>;
 		};
 
-		aux_bus: aux_bus {
+		aux_bus: aux-bus {
 			#address-cells = <2>;
 			#size-cells = <2>;
 			compatible = "simple-bus";

arch/arm64/boot/dts/freescale/fsl-ls1046a.dtsi

@@ -715,7 +715,7 @@
 					    QORIQ_CLK_PLL_DIV(2)>;
 		};
 
-		aux_bus: aux_bus {
+		aux_bus: aux-bus {
 			#address-cells = <2>;
 			#size-cells = <2>;
 			compatible = "simple-bus";