selftests: devlink: undo changes at the end of resource_test

The netdevsim object is reused by all the tests, but the resource
tests puts it into a broken state (failed reload in a different
namespace). Make sure it's fixed up at the end of that test
otherwise subsequent tests fail.

Fixes: b74c37fd ("selftests: netdevsim: add tests for devlink reload with resources")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>