realtek: fix cpu port link type

Some DTS files have a qsgmii link mode for the CPU port. This does
not harm but it is wrong. The CPU port of the realtek switch is always
directly connected to the switch by some unknown wiring and should
therefore be described as internal. Align the wrongly defined DTS
files to the standard.

Signed-off-by: Markus Stockhausen <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/18691
Signed-off-by: Robert Marko <[email protected]>

target/linux/realtek/dts/rtl8393_d-link_dgs-1210-52.dts

@@ -153,7 +153,7 @@
 		port@52 {
 			ethernet = <&ethernet0>;
 			reg = <52>;
-			phy-mode = "qsgmii";
+			phy-mode = "internal";
 			fixed-link {
 				speed = <1000>;
 				full-duplex;

target/linux/realtek/dts/rtl8393_netgear_gs750e.dts

@@ -243,7 +243,7 @@
 		port@52 {
 			ethernet = <&ethernet0>;
 			reg = <52>;
-			phy-mode = "qsgmii";
+			phy-mode = "internal";
 			fixed-link {
 				speed = <1000>;
 				full-duplex;

target/linux/realtek/dts/rtl8393_zyxel_gs1900-48.dts

@@ -313,7 +313,7 @@
 		port@52 {
 			ethernet = <&ethernet0>;
 			reg = <52>;
-			phy-mode = "qsgmii";
+			phy-mode = "internal";
 			fixed-link {
 				speed = <1000>;
 				full-duplex;