lantiq: clarify VG3503J name

Append the ECI model to the device name, to avoid confusion with the
older model.

Signed-off-by: Alex Maclean <[email protected]>

target/linux/lantiq/image/Makefile

@@ -515,7 +515,7 @@ TARGET_DEVICES += FRITZ7360SL
 
 define Device/VG3503J
   IMAGE_SIZE := 8000k
-  DEVICE_TITLE := BT OpenReach - ECI VDSL Modem
+  DEVICE_TITLE := BT OpenReach - ECI VDSL Modem V-2FUb/R
 endef
 TARGET_DEVICES += VG3503J