lantiq: fix regression in VG3503J.dts

9d0608eef3e5b9fca - "lantiq: VG3503J - merge profiles"

resulted in the dts file missing the version string.

Signed-off-by: John Crispin <[email protected]>

target/linux/lantiq/dts/VG3503J.dts

@@ -1,3 +1,5 @@
+/dts-v1/;
+
 /include/ "vr9.dtsi"
 
 / {