OrangePi 5b emmc support

Armbian image from https://www.armbian.com/orangepi-5/ by default thinks that the board is 5, not 5b, so no nice emmc storage for you! I thought that it’s kind of general issue with the kernel, but all it took is to change fdtfile to rockchip/rk3588s-orangepi-5b.dtb in the /boot/armbianEnv.txt. Now my /var with all K3S and rancher stuff is on a fast reliable emmc, not sd-card.