lantiq: use soc_vendor_device scheme on DTS file

This renames lantiq DTS(I) files to follow soc_vendor_device scheme.
This will make DTS files easier to maintain.

As a side effect, DTS file name can be derived from device node
names now, only having to specify a SOC variable in Makefiles.

While at it, move files to arch/mips/boot/dts/lantiq subfolder.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/lantiq/image/tp-link.mk

@@ -2,6 +2,7 @@ DEVICE_VARS += TPLINK_FLASHLAYOUT TPLINK_HWID TPLINK_HWREV TPLINK_HWREVADD TPLIN
 
 define Device/lantiqTpLink
   DEVICE_VENDOR := TP-Link
+  SOC := vr9
   TPLINK_HWREVADD := 0
   TPLINK_HVERSION := 2
   KERNEL := kernel-bin | append-dtb | lzma
@@ -16,7 +17,6 @@ define Device/tplink_tdw8970
   $(Device/lantiqTpLink)
   DEVICE_MODEL := TD-W8970
   DEVICE_VARIANT := v1
-  DEVICE_DTS := TDW8970
   TPLINK_FLASHLAYOUT := 8Mltq
   TPLINK_HWID := 0x89700001
   TPLINK_HWREV := 1
@@ -30,7 +30,6 @@ define Device/tplink_tdw8980
   $(Device/lantiqTpLink)
   DEVICE_MODEL := TD-W8980
   DEVICE_VARIANT := v1
-  DEVICE_DTS := TDW8980
   TPLINK_FLASHLAYOUT := 8Mltq
   TPLINK_HWID := 0x89800001
   TPLINK_HWREV := 14
@@ -44,7 +43,6 @@ define Device/tplink_vr200
   $(Device/lantiqTpLink)
   DEVICE_MODEL := Archer VR200
   DEVICE_VARIANT := v1
-  DEVICE_DTS := VR200
   TPLINK_FLASHLAYOUT := 16Mltq
   TPLINK_HWID := 0x63e64801
   TPLINK_HWREV := 0x53
@@ -58,7 +56,6 @@ define Device/tplink_vr200v
   $(Device/lantiqTpLink)
   DEVICE_MODEL := Archer VR200v
   DEVICE_VARIANT := v1
-  DEVICE_DTS := VR200v
   TPLINK_FLASHLAYOUT := 16Mltq
   TPLINK_HWID := 0x73b70801
   TPLINK_HWREV := 0x2f