image-resin: ln -> ln -f
image-resin: ln -> ln -f

Without the -f, the build can be performed only once. The second build
will fail with "File exists".

Signed-off-by: Michal Mazurek <a2df1e659c9fd2578de0a26565357cb273292eeb@resin.io>

resin-os/meta-resin,resin-os/meta-resin,resin-os/meta-resin,resin-os/meta-resin