kernel-devsrc: Ensure we don't race against do_make_scripts from module-base.bbclass
do_install for kernel-devsrc can race against do_make_scripts from
module-base.bbclass. Since there is a lock there to guard against concurrency
already, we can just use it here to avoid a race.
Ultimately, this can all likely be much more streamlined but this resolves
the immediate build failures.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>