qualcommax: ipq807x: uboot-envtools: yuncore ax880

qualcommax: ipq807x: uboot-envtools: yuncore ax880

There was no config in the uboot-envtools package, so there is no
generated /etc/fw_env.config for the fw_printenv and fw_setenv utils.
Since uboot-envtools 2024.01, there is a way to make these utils work
without /etc/fw_env.config if the DT has an env partition with the prop.:

compatible = "u-boot,env";

So, this commit adds the prop. above to the appsblenv:0 partition
in the yuncore ax880 DTS file.

Signed-off-by: Isaev Ruslan <legale.legale@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/15305
Signed-off-by: Robert Marko <robimarko@gmail.com>