selftests: spectrum-2: Fix multiple_masks_test

With recent fix in C-TCAM spillage for delta masks, the test stops to be
falsely positive. So fix it not to use delta by adding src_ip bits to the
masks. Alongside with that, use C-TCAM spill trace to see when the
spillage actually happens.

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>