rampis: mt7621: Edgerouter-X set compat version message

Refer user to the wiki page for instructions on how to migrate to the
new kernel layout.

Signed-off-by: Tim Lunn <[email protected]>
Tested-by: Mauri Sandberg <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/15194
(cherry picked from commit 70c371d91cda300d7c655f019cb2076d2dd537fb)
Link: https://github.com/openwrt/openwrt/pull/17097
Signed-off-by: Petr Štetiar <[email protected]>

target/linux/ramips/image/mt7621.mk

@@ -2865,6 +2865,10 @@ define Device/ubnt_edgerouter_common
 	ubnt-erx-factory-image $(KDIR)/tmp/$$(KERNEL_INITRAMFS_PREFIX)-factory.tar
   IMAGE/sysupgrade.bin := sysupgrade-tar | append-metadata
   DEVICE_PACKAGES += -wpad-basic-mbedtls -uboot-envtools
+  DEVICE_COMPAT_VERSION := 2.0
+  DEVICE_COMPAT_MESSAGE :=  Partition table has been changed due to kernel size restrictions. \
+    Refer to the wiki page for instructions to migrate to the new layout: \
+    https://openwrt.org/toh/ubiquiti/edgerouter_x_er-x_ka
   DEFAULT := n
 endef