net/mlx5: E-Switch, Handle UC address change in switchdev mode

When NVME device emulation mode is enabled, more than one PFs use the
same physical port. In this case, MPFS is required to program L2
addresses.

It used to rely on netdev set_rx_mode in switchdev mode, but driver
later changed to not create netdev for eswitch manager once in
switchdev mode. So, UC address event should be handled.

Signed-off-by: Bodong Wang <bodong@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>