base-files: add generic preinit script to extract board/model info from device-tree

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 45462

package/base-files/files/lib/preinit/90_sysinfo

+do_sysinfo_generic() {
+	[ -d /proc/device-tree ] || return
+	mkdir -p /tmp/sysinfo
+	[ -e /tmp/sysinfo/board_name ] || \
+		echo "$(strings /proc/device-tree/compatible | head -1)" > /tmp/sysinfo/board_name
+	[ -e /tmp/sysinfo/model ] || \
+		echo "$(cat /proc/device-tree/model)" > /tmp/sysinfo/model
+}
+
+boot_hook_add preinit_main do_sysinfo_generic