selftests: net: Fix netdev name mismatch in cleanup

lag_lib.sh creates the interfaces dummy1 and dummy2 whereas
dev_addr_lists.sh:destroy() deletes the interfaces dummy0 and dummy1. Fix
the mismatch in names.

Fixes: bbb774d9 ("net: Add tests for bonding and team address list management")
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Reviewed-by: Jonathan Toppins <jtoppins@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>