tc-testing: initial tdc selftests for cls_u32

- move test "e9a3 - Add u32 with source match" to u32.json, and change the
  match pattern to catch all hnodes
- add testcases for relevant error paths of cls_u32 module

Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>