net/mlx5: Bridge, support LAG

Allow adding bond net devices to mlx5 bridge with following changes:

- Modify bridge representor code to obtain uplink represetor that belongs
to eswitch that is registered for notification. Require representor to be
in shared FDB mode. If representor is the lag master, then consider its
port as local, otherwise treat it as peer.

- Use devcom to match on paired eswitch metadata in peer FDB entries. This
is necessary for shared FDB LAG to function since packets are always
received on active eswitch instance as opposed to parent eswitch of port.

- Support for deleting peer flows when receiving
SWITCHDEV_FDB_DEL_TO_BRIDGE notification was implemented in one of previous
patches in series. Now also implement support for handling
SWITCHDEV_FDB_ADD_TO_BRIDGE which can be generated on peer by bridge update
workqueue task in LAG configuration. Refresh the flow 'lastuse' timestamp
to current jiffies when receiving such notification on eswitch that manages
the local FDB entry. This allows peer entries to prevent ageing of the FDB.

Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>