arm64: dts: imx8mq-nitrogen: Fix PCA9546 I2C subnodes

Per i2c-mux-pca954x.yaml, the PCA9546 I2C subnodes should be in the
'i2c@' format.

Change it accordingly to fix the following schema warning:

imx8mm-nitrogen-r2.dtb: i2c-mux@70: Unevaluated properties are not allowed ('i2c3@0' was unexpected)
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/boot/dts/freescale/imx8mq-nitrogen.dts

@@ -142,7 +142,7 @@ i2c-mux@70 {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		i2c1a: i2c1@0 {
+		i2c1a: i2c@0 {
 			reg = <0>;
 			#address-cells = <1>;
 			#size-cells = <0>;
@@ -159,7 +159,7 @@ reg_arm_dram: regulator@60 {
 			};
 		};
 
-		i2c1b: i2c1@1 {
+		i2c1b: i2c@1 {
 			reg = <1>;
 			#address-cells = <1>;
 			#size-cells = <0>;
@@ -176,7 +176,7 @@ reg_dram_1p1v: regulator@60 {
 			};
 		};
 
-		i2c1c: i2c1@2 {
+		i2c1c: i2c@2 {
 			reg = <2>;
 			#address-cells = <1>;
 			#size-cells = <0>;
@@ -193,7 +193,7 @@ reg_soc_gpu_vpu: regulator@60 {
 			};
 		};
 
-		i2c1d: i2c1@3 {
+		i2c1d: i2c@3 {
 			reg = <3>;
 			#address-cells = <1>;
 			#size-cells = <0>;
@@ -222,7 +222,7 @@ pca9546: i2c-mux@70 {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		i2c4@0 {
+		i2c@0 {
 			reg = <0>;
 			#address-cells = <1>;
 			#size-cells = <0>;
@@ -257,14 +257,14 @@ lt8912_out: endpoint {
 			};
 		};
 
-		ddc_i2c_bus: i2c4@1 {
+		ddc_i2c_bus: i2c@1 {
 			reg = <1>;
 			#address-cells = <1>;
 			#size-cells = <0>;
 			clock-frequency = <100000>;
 		};
 
-		i2c4@3 {
+		i2c@3 {
 			reg = <3>;
 			#address-cells = <1>;
 			#size-cells = <0>;