IB/addr: Store net_device type instead of translating to RDMA transport

The struct rdma_dev_addr stores net_device address information:
the source device address, destination hardware address, and
broadcast address.  For consistency, store the net_device type
rather than converting it to the rdma_node_type.

The type indicates the format of the various hardware addresses,
which is what we're concerned with, and not the RDMA node type
that the address may map to.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>