Purge s5p6818 board family

The family consists of 4 boards, but hasn't seen any activity in years,
is unmaintained, stuck on EOL Linux 4.14 and the bootloader does
not build.

config/bootscripts/boot-s5p6818.cmd

@@ -1,40 +0,0 @@
-# DO NOT EDIT THIS FILE
-#
-# Please edit /boot/armbianEnv.txt to set supported parameters
-#
-
-# default values
-setenv rootdev "/dev/mmcblk2p1"
-setenv rootfstype "ext4"
-setenv verbosity "1"
-setenv bootlogo "false"
-setenv fdt_addr "0x48000000"
-setenv ramdisk_addr_r "0x49000000"
-setenv kernel_addr_r "0x4a000000"
-
-# fdtfile should come from compile-time u-boot patches
-if test -z "${fdtfile}"; then
-	setenv fdtfile "s5p6818-nanopi-m3.dtb"
-fi
-
-echo "Boot script loaded from SD card ${devnum}"
-
-if ext4load mmc ${devnum}:1 ${kernel_addr_r} ${prefix}/armbianEnv.txt; then
-	env import -t ${kernel_addr_r} ${filesize}
-fi
-
-if test "${bootlogo}" = "true"; then
-	setenv consoleargs "splash plymouth.ignore-serial-consoles ${consoleargs}"
-else
-	setenv consoleargs "splash=verbose ${consoleargs}"
-fi
-
-setenv bootargs "console=ttySAC0,115200n8 console=tty1 ${consoleargs}  root=${rootdev} rootwait rootfstype=${rootfstype} loglevel=${verbosity} usb-storage.quirks=${usbstoragequirks} ${extraargs}"
-
-if ext4load mmc ${devnum}:1 ${fdt_addr} ${prefix}dtb/nexell/${fdtfile} || ext4load mmc 1:1 ${fdt_addr} ${prefix}dtb/nexell/s5p6818-nanopi3-rev07.dtb; then echo "Loading DTB"; fi
-ext4load mmc ${devnum}:1 ${ramdisk_addr_r} ${prefix}uInitrd
-ext4load mmc ${devnum}:1 ${kernel_addr_r} ${prefix}Image
-booti ${kernel_addr_r} ${ramdisk_addr_r} ${fdt_addr}
-
-# Recompile with:
-# mkimage -C none -A arm -T script -d /boot/boot.cmd /boot/boot.scr