arm64: dts: ti: k3-am64: Convert serdes_ln_ctrl node into reg-mux

This removes a dependency on the parent node being a syscon node.
Convert from mmio-mux to reg-mux adjusting node name and properties
as needed.
Signed-off-by: Andrew Davis <afd@ti.com>
Link: https://lore.kernel.org/r/20240124184722.150615-1-afd@ti.comSigned-off-by: Vignesh Raghavendra <vigneshr@ti.com>

arch/arm64/boot/dts/ti/k3-am64-main.dtsi

@@ -51,10 +51,11 @@ chipid@14 {
 			reg = <0x00000014 0x4>;
 		};
 
-		serdes_ln_ctrl: mux-controller {
-			compatible = "mmio-mux";
+		serdes_ln_ctrl: mux-controller@4080 {
+			compatible = "reg-mux";
+			reg = <0x4080 0x4>;
 			#mux-control-cells = <1>;
-			mux-reg-masks = <0x4080 0x3>; /* SERDES0 lane0 select */
+			mux-reg-masks = <0x0 0x3>; /* SERDES0 lane0 select */
 		};
 
 		phy_gmii_sel: phy@4044 {