As mkits.sh only generates the relevant DTS for mkimage and is
specific for the building image, we can move it outside the locked
section as it doesn't do any operation that can be used concurrently by
others.
This won't have any real impact but clean the code making it clear what
needs to be protected and what can be executed concurrently.
Link: https://github.com/openwrt/openwrt/pull/20492
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
5a42ed1138
