arm64: dts: ti: k3-*: fix fss node dtbs check warnings

Fix these fss node warnings that dtbs_check throws:

fss@47000000: $nodename:0: 'fss@47000000' does not match
'^([a-z][a-z0-9\\-]+-bus|bus|localbus|soc|axi|ahb|apb)(@.+)?$'

By renaming fss to bus.

Cc: Nishant Menon <nm@ti.com>
Suggested-by: Andrew Davis <afd@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Reviewed-by: Reid Tonking <reidt@ti.com>
Link: https://lore.kernel.org/r/20230810081847.277094-1-d-gole@ti.comSigned-off-by: Nishanth Menon <nm@ti.com>

arch/arm64/boot/dts/ti/k3-am65-mcu.dtsi

@@ -278,7 +278,7 @@ m_can1: can@40568000 {
 		status = "disabled";
 	};
 
-	fss: fss@47000000 {
+	fss: bus@47000000 {
 		compatible = "simple-bus";
 		#address-cells = <2>;
 		#size-cells = <2>;

arch/arm64/boot/dts/ti/k3-j721e-mcu-wakeup.dtsi

@@ -337,7 +337,7 @@ wkup_i2c0: i2c@42120000 {
 		status = "disabled";
 	};
 
-	fss: fss@47000000 {
+	fss: bus@47000000 {
 		compatible = "simple-bus";
 		reg = <0x0 0x47000000 0x0 0x100>;
 		#address-cells = <2>;