selftests: mlxsw: Add forwarding test for RIF MAC profiles

Verify that MAC profile changes are indeed applied and that packets are
forwarded with the correct source MAC.

Output example:

$ ./rif_mac_profiles.sh
TEST: h1->h2: new mac profile                                       [ OK ]
TEST: h2->h1: new mac profile                                       [ OK ]
TEST: h1->h2: edit mac profile                                      [ OK ]
TEST: h2->h1: edit mac profile                                      [ OK ]

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>