mixtile-edge2: add rk3568 board (current/edge/vendor)

- in main `rockchip64` family, for current/edge
- using mainline u-boot's generic rk3568 for current/edge
- vendor kernel is added via a copypasta hook to piggyback on `rk35xx`
  - requires armbian/linux-rockchip PR armbian/linux-rockchip#245
- vendor u-boot:
  - is required to bringup npu for vendor kernel (otherwise panics)
  - .dts done based on vendor kernel DT + looking at armsom-sige3
  - defconfig ripped off from armsom-sige3

config/boards/mixtile-edge2.wip

@@ -0,0 +1,54 @@
+# Rockchip RK3568 quad core 4GB-8GB GBE PCIe USB3 SATA NVMe
+BOARD_NAME="Mixtile Edge 2"
+BOARDFAMILY="rockchip64"
+BOARD_MAINTAINER=""
+BOOT_SOC="rk3568"
+KERNEL_TARGET="current,edge,vendor"
+BOOT_FDT_FILE="rockchip/rk3568-mixtile-edge2.dtb"
+IMAGE_PARTITION_TABLE="gpt"
+FULL_DESKTOP="yes"
+BOOT_LOGO="desktop"
+SRC_CMDLINE="earlycon=uart8250,mmio32,0xfe660000 loglevel=7 console=ttyS2,1500000" # for extlinux / EXT=u-boot-menu
+
+# Mainline U-Boot
+function post_family_config__h96_max_use_mainline_uboot() {
+	if [[ "${BRANCH}" == "vendor" || "${BRANCH}" == "legacy" ]]; then
+		display_alert "$BOARD" "Using vendor U-Boot for $BOARD / $BRANCH" "info" # See below hook
+		return
+	fi
+
+	display_alert "$BOARD" "Using mainline U-Boot for $BOARD / $BRANCH" "info"
+
+	declare -g BOOTCONFIG="generic-rk3568_defconfig"             # Use generic defconfig which should boot all RK3568 boards
+	declare -g BOOTSOURCE="https://github.com/u-boot/u-boot.git" # We ❤️ Mainline U-Boot
+	declare -g BOOTBRANCH="tag:v2024.07"
+	declare -g BOOTPATCHDIR="v2024.07/board_${BOARD}"
+	declare -g BOOTDIR="u-boot-${BOARD}" # do not share u-boot directory
+
+	declare -g UBOOT_TARGET_MAP="BL31=${RKBIN_DIR}/${BL31_BLOB} ROCKCHIP_TPL=${RKBIN_DIR}/${DDR_BLOB};;u-boot-rockchip.bin"
+
+	# Disable stuff from rockchip64_common; we're using binman here which does all the work already
+	unset uboot_custom_postprocess write_uboot_platform write_uboot_platform_mtd
+
+	# Just use the binman-provided u-boot-rockchip.bin, which is ready-to-go
+	function write_uboot_platform() {
+		dd "if=$1/u-boot-rockchip.bin" "of=$2" bs=32k seek=1 conv=notrunc status=none
+	}
+}
+
+function post_family_config_branch_vendor__kernel_and_uboot_rk35xx_mixtile_edge2() {
+	# Copypasta from rockchip-rk3588.conf family file -- we _really_ gotta find a better way!
+	declare -g KERNEL_MAJOR_MINOR="6.1" # Major and minor versions of this kernel.
+	declare -g KERNELSOURCE='https://github.com/armbian/linux-rockchip.git'
+	declare -g KERNELBRANCH='branch:rk-6.1-rkr3'
+	declare -g KERNELPATCHDIR='rk35xx-vendor-6.1'
+	declare -g LINUXFAMILY=rk35xx
+	declare -g -i KERNEL_GIT_CACHE_TTL=120 # 2 minutes
+	declare -g OVERLAY_PREFIX='rk35xx'
+
+	# Use vendor u-boot, same as rk35xx; we've a defconfig and dt in there
+	declare -g BOOTSOURCE='https://github.com/radxa/u-boot.git'
+	declare -g BOOTBRANCH='branch:next-dev-v2024.03' # Always use same version as rk3588, they share a patch dir
+	declare -g BOOTPATCHDIR="legacy/u-boot-radxa-rk35xx"
+	declare -g BOOTCONFIG="mixtile-edge2-rk3568_defconfig"
+}