arm64: dts: ti: k3-j721e-main: rename smmu node to iommu

Rename smmu node to iommu to fix dtbs_check warning:
 k3-j721e-common-proc-board.dt.yaml: smmu@36600000: $nodename:0: 'smmu@36600000' does not match '^iommu@[0-9a-f]*'
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>

arch/arm64/boot/dts/ti/k3-j721e-main.dtsi

@@ -95,7 +95,7 @@ secure_proxy_main: mailbox@32c00000 {
 			interrupts = <GIC_SPI 37 IRQ_TYPE_LEVEL_HIGH>;
 		};
 
-		smmu0: smmu@36600000 {
+		smmu0: iommu@36600000 {
 			compatible = "arm,smmu-v3";
 			reg = <0x0 0x36600000 0x0 0x100000>;
 			interrupt-parent = <&gic500>;