treewide: use only board_name function to get name

Do not parse /tmp/sysinfo/board_name, /proc/cpuinfo or the device tree
compatible string directly. Always use the board_name function to get
the board name.

The admswconfig package still reads /proc/cpuinfo directly. The code
looks somehow broken and the whole adm5120 which uses this package
looks unmaintained. Leave it as it is for now.

Signed-off-by: Mathias Kresin <dev@kresin.me>

target/linux/octeon/base-files/lib/preinit/79_move_config

@@ -2,7 +2,9 @@
 # Copyright (C) 2014 OpenWrt.org
 
 move_config() {
-	case "$(cat /tmp/sysinfo/board_name)" in
+	. /lib/functions.sh
+
+	case "$(board_name)" in
 		erlite)
 			mount -t vfat /dev/sda1 /mnt
 			[ -f /mnt/sysupgrade.tgz ] && mv -f /mnt/sysupgrade.tgz /