net/mlx5: E-Switch, Add API to create send-to-vport rules

Add the API to create send-to-vport e-switch rules of the form

 packet meta-data :: send-queue-number == $SQN and source-vport == 0 --> $VPORT

These rules are to be used for a send-to-vport logic which conceptually bypasses
the "normal" steering rules currently present at the e-switch datapath.

Such rule should apply only for packets that originate in the e-switch manager
vport (0) and are sent for a given SQN which is used by a given VF representor
device, and hence the matching logic.

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