net/mlx5: E-Switch, Add SR-IOV (FDB) support

Enabling E-Switch SRIOV for nvfs+1 vports.

Create E-Switch FDB for L2 UC/MC mac steering between VFs/PF and
external vport (Uplink).

FDB contains forwarding rules such as:
	UC MAC0 -> vport0(PF).
	UC MAC1 -> vport1.
	UC MAC2 -> vport2.
	MC MACX -> vport0, vport2, Uplink.
	MC MACY -> vport1, Uplink.

For unmatched traffic FDB has the following default rules:
	Unmached Traffic (src vport != Uplink) -> Uplink.
	Unmached Traffic (src vport == Uplink) -> vport0(PF).

FDB rules population:
Each NIC vport (VF) will notify E-Switch manager of its UC/MC vport
context changes via modify vport context command, which will be
translated to an event that will be handled by E-Switch manager (PF)
which will update FDB table accordingly.

Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>