rb532: switch to UBI, drop yaffs2 support, use sysupgrade for NAND

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

target/linux/rb532/base-files/lib/preinit/10_sysinfo

@@ -0,0 +1,11 @@
+get_model_rb532() {
+	grep system\ type /proc/cpuinfo | awk -F ": " '{print $2}'
+}
+
+do_sysinfo_rb532() {
+	mkdir -p /tmp/sysinfo
+	echo rb532 > /tmp/sysinfo/board_name
+	get_model_rb532 > /tmp/sysinfo/model
+}
+
+boot_hook_add preinit_main do_sysinfo_rb532