WIP: mediatek: add bpi-r3-mini

What works:
 * Ethernet with Airoha EN8811H PHYs
 * WiFi
 * USB
 * booting from SPI-NAND
 * booting from eMMC
 * PWM fan
 * CPU thermal sensor
 * controllable LEDs (incl. all 4 PHY LEDs)
 * reset button

Untested:
 * M.2 NVMe (PCIe)
 * M.2 LTE modem (USB 3)

Partially based on immortalwrt support for the R3 mini, big thanks for
doing the ground work!

package/boot/uboot-envtools/files/mediatek_filogic

@@ -37,6 +37,7 @@ asus,rt-ax59u)
 	ubootenv_add_uci_config "/dev/mtd0" "0x100000" "0x20000" "0x20000"
 	;;
 bananapi,bpi-r3|\
+bananapi,bpi-r3-mini|\
 bananapi,bpi-r4)
 	. /lib/upgrade/platform.sh
 

target/linux/mediatek/base-files/etc/uci-defaults/99_fwenv-store-ethaddr.sh

@@ -9,7 +9,8 @@ unielec,u7623-02)
 	[ -z "$(fw_printenv -n ethaddr 2>/dev/null)" ] &&
 		fw_setenv ethaddr "$(cat /sys/class/net/eth0/address)"
 	;;
-bananapi,bpi-r3)
+bananapi,bpi-r3|\
+bananapi,bpi-r3-mini)
 	[ -z "$(fw_printenv -n ethaddr 2>/dev/null)" ] &&
 		fw_setenv ethaddr "$(cat /sys/class/net/eth0/address)"
 	[ -z "$(fw_printenv -n eth1addr 2>/dev/null)" ] &&