selftests: mlxsw: Add a test case for MAC profiles consolidation

Add a test case to cover the bug fixed by the previous patch.

Edit the MAC address of one netdev so that it matches the MAC address of
the second netdev. Verify that the two MAC profiles were consolidated by
testing that the MAC profiles occupancy decreased by one.

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>