realtek: enable in-band configuration of SFP port on ZyXEL XGS1250-12

The rtl93xx SoC supports both 1000Base-X and 10GBase-CR on its SerDes
interfaces. Enable dynamic switching between mac-signaled modes to
support 1000Base-X and 10GBase-CR on the SFP port.

Signed-off-by: Tobias Schramm <[email protected]>

target/linux/realtek/dts-5.15/rtl9302_zyxel_xgs1250-12.dts

@@ -300,17 +300,11 @@
 		port@27 {
 			reg = <27>;
 			label = "lan12";
-			phy-mode = "10gbase-r";
+			phy-mode = "1000base-x";
 			phy-handle = <&phy27>;
 			sfp = <&sfp0>;
 			led-set = <2>;
-
-			fixed-link {
-				speed = <10000>;
-				full-duplex;
-				pause;
-			};
-
+			managed = "in-band-status";
 		};
 
 		port@28 {