Add infrastructure to l3mdev (the core code for Layer 3 master devices) in
order to find out the corresponding VRF device for a given table id.
Therefore, the l3mdev implementations:
- can register a callback that returns the device index of the l3mdev
associated with a given table id;
- can offer the lookup function (table to VRF device).
Signed-off-by: Andrea Mayer <andrea.mayer@uniroma2.it>
Signed-off-by: David S. Miller <davem@davemloft.net>