selftests: mlxsw: Add Bloom delta test

The eRP table is active when there is more than a single rule
pattern. It may be that the patterns are close enough and use delta
mechanism. Bloom filter index computation is based on the values of
{rule & mask, mask ID, region ID} where the rule delta bits must be
cleared.

Add a test that exercises Bloom filter with delta mechanism.
Configure rules within delta range and pass a packet which is
supposed to hit the correct rule.

Signed-off-by: Nir Dotan <nird@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>