AK3: unlock blocks before flash to handle post-incremental-OTA cases

tools/ak3-core.sh

@@ -391,6 +391,7 @@ flash_boot() {
   elif [ "$(wc -c < boot-new.img)" -gt "$(wc -c < boot.img)" ]; then
     abort "New image larger than boot partition. Aborting...";
   fi;
+  blockdev --setrw $block 2>/dev/null;
   if [ -f "$bin/flash_erase" -a -f "$bin/nandwrite" ]; then
     $bin/flash_erase $block 0 0;
     $bin/nandwrite -p $block boot-new.img;
@@ -422,6 +423,7 @@ flash_dtbo() {
     if [ ! -e "$dtboblock" ]; then
       abort "dtbo partition could not be found. Aborting...";
     fi;
+    blockdev --setrw $dtboblock 2>/dev/null;
     if [ -f "$bin/flash_erase" -a -f "$bin/nandwrite" ]; then
       $bin/flash_erase $dtboblock 0 0;
       $bin/nandwrite -p $dtboblock $dtbo;