lantiq: adapt gpio-stp-xway node name to get clock

The MIPS code assigns the clock node based on the device tree node name.
This name was renamed with kernel 6.12.58 and v6.6.117. Adapt our out of
tree device tree files to this rename to fix loading the STP GPIO
driver.

Without this fix the driver fails like this:
```
[    0.320000] gpio-stp-xway 1e100bb0.stp: Failed to get clock
[    0.330000] gpio-stp-xway 1e100bb0.stp: probe with driver gpio-stp-xway failed with error -2
```

Link: https://git.kernel.org/linus/b0d04fe6a633ada2c7bc1b5ddd011cbd85961868
Fixes: openwrt/openwrt#21697
Co-Authored-By: Shiji Yang <yangshiji66@outlook.com>
Link: openwrt/openwrt#22444
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit d405685)
[Fix danube.dtsi too]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

Author: hauke

target/linux/lantiq/files/arch/mips/boot/dts/lantiq/ar9.dtsi

@@ -314,7 +314,7 @@
 			};
 		};
 
-		stp: stp@e100bb0 {
+		stp: gpio@e100bb0 {
 			#gpio-cells = <2>;
 			compatible = "lantiq,gpio-stp-xway";
 			gpio-controller;

target/linux/lantiq/files/arch/mips/boot/dts/lantiq/danube.dtsi

@@ -141,7 +141,7 @@
 			interrupts = <126 127 128 129 130 131>;
 		};
 
-		gpios: stp@e100bb0 {
+		gpios: gpio@e100bb0 {
 			#gpio-cells = <2>;
 			compatible = "lantiq,gpio-stp-xway";
 			gpio-controller;

target/linux/lantiq/files/arch/mips/boot/dts/lantiq/vr9.dtsi

@@ -354,7 +354,7 @@
 			};
 		};
 
-		stp: stp@e100bb0 {
+		stp: gpio@e100bb0 {
 			status = "disabled";
 			compatible = "lantiq,gpio-stp-xway";
 			reg = <0xe100bb0 0x40>;