octeon: ubnt-usg: add board name to supported devices

The on-device board name reported by 'ubus call system board' is not present
in the generated profiles.json.  This results in upgrade tools being unable
to match the image with the proper device.  Let's add a 'SUPPORTED_DEVICES'
entry for the board name to fix this.

Links: https://forum.openwrt.org/t/owut-openwrt-upgrade-tool/200035/441
Links: https://github.com/openwrt/openwrt/commit/2a07270180ed0e295d854d6e9e59c78c40549efc
Signed-off-by: Eric Fahlgren <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/17736
Signed-off-by: Hauke Mehrtens <[email protected]>
(cherry picked from commit 7165937c3b6ebe5ac692fcde1cc69ba1c7a3d9c9)

target/linux/octeon/image/Makefile

@@ -92,6 +92,7 @@ define Device/ubnt_unifi-usg
   DEVICE_PACKAGES += kmod-gpio-button-hotplug kmod-leds-gpio
   DEVICE_DTS := cn5020_ubnt_usg
   KERNEL += | append-dtb-to-elf
+  SUPPORTED_DEVICES += ubnt,usg
 endef
 TARGET_DEVICES += ubnt_unifi-usg