radxa-e24c: enable edge branch by picking from Kwiboo's WiP tree

- works pretty nice (albeit no USB support in kernel, only u-boot)
- this is still `WiP`: once Kwiboo lands his rk3528 patchset,
  most of this will change / be much simpler. Just be patient!
- Important: the Realtek DSA switch chip is not really understood
  by the likes of NetworkManager and systemd-networkd; they'll think
  the board has 4 ethernet interfaces, which is not really true.
  Only one real MAC address (the SoC's GMAC) exists; in front of it
  is a programmable switch; to make it work one needs custom setup
  to bridge the LANx ports and keep WAN separate. Even then, the
  WAN port will have the same MAC as LANx and needs to be really
  used on a separate physical network, otherwise chaos/conflicts.
  For simple usage/testing, I recommend to connect only LAN1 and
  disable the other ports in NetworkManager after the first boot.
- Note: `edge` u-boot can be written to MTD/SPI-FLASH and works.
  But keep in mind  it _cannot_ boot the vendor kernel (it hangs
  during pcie init); might work when booting from SD, if pcie is
  not enumerated by u-boot.

Author: rpardini

config/boards/radxa-e24c.wip

@@ -3,10 +3,10 @@ BOARD_NAME="Radxa E24C"
 BOARD_VENDOR="radxa"
 BOARDFAMILY="rockchip-rk3588"
 BOARD_MAINTAINER="rpardini"
-BOOTCONFIG="radxa-e24c-spi-rk3528_defconfig"       # vendor uboot defconfig; Radxa's name
-KERNEL_TARGET="vendor"                             # edge (6.18) is not ready yet: ,edge
-BOOT_FDT_FILE="rockchip/rk3528-radxa-e24c-spi.dtb" # for non-eMMC boards, with SPI NOR: "SF: Detected mx25u12835f with page size 256 Bytes, erase size 4 KiB, total 16 MiB"
-#BOOT_FDT_FILE="rockchip/rk3528-radxa-e24c.dtb"    # for eMMC boards
+BOOTCONFIG="radxa-e24c-spi-rk3528_defconfig"       # same name across vendor and mainline
+KERNEL_TARGET="edge,vendor"                        # edge (6.18+) is still not ready, many patches required. keep an eye on Kwiboo
+BOOT_FDT_FILE="rockchip/rk3528-radxa-e24c-spi.dtb" # same name across vendor and mainline; for SPI boards
+#BOOT_FDT_FILE="rockchip/rk3528-radxa-e24c.dtb"    # same name across vendor and mainline; for eMMC boards
 BOOT_SCENARIO="spl-blobs"
 BOOT_SOC="rk3528"
 IMAGE_PARTITION_TABLE="gpt"