cve-check: fix symlinks where link and output path are equal

An if statement now checks if the link and output path are
the same, if they are then the link is not created,
otherwise it is.

Signed-off-by: Davide Gardenal <davide.gardenal@huawei.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>