lantiq: enable STP where referenced

While moving common used parts to dtsi files, the was disabled by
default but not enabled for all boards using the STP.

Fixes: f519fea4c6 ("lantiq: kernel 4.14: cleanup dts files")

Reported-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Mathias Kresin <dev@kresin.me>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

target/linux/lantiq/files-4.14/arch/mips/boot/dts/P2601HNFX.dts

@@ -181,6 +181,7 @@
 };
 
 &stp {
+	status = "okay";
 	lantiq,shadow = <0xfff>;
 	lantiq,groups = <0x3>;
 };

target/linux/lantiq/files-4.14/arch/mips/boot/dts/VGV7519.dtsi

@@ -279,6 +279,7 @@
 };
 
 &stp {
+	status = "okay";
 	lantiq,shadow = <0xffff>;
 	lantiq,groups = <0x3>;
 	lantiq,dsl = <0x0>;