When port is added to a bridge, the old code would send the new neighbor
netlink message before the subsequent new link message. This bug makes
it difficult to use the monitoring API in an application.

This code changes the ordering to add the forwarding entry
after the port is setup. One of the error checks (for invalid address)
is moved earlier in the process to avoid having to do unwind.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>