zebra: Allow FreeBSD to set and delete addresses from an interface

zebra: Allow FreeBSD to set and delete addresses from an interface

This series of events:

$ sudo ifconfig lo0 add 4.4.4.4/32
$ sudo ifconfig lo0 inet 4.4.4.4/32 delete

would end up leaving the 4.4.4.4/32 address on the interface under
freebsd.

This all boils down to the fact that the interface is not
considered connected yet we have a destination.  If the
destination is the same and we are not connected ignore
it on freebsd.

I am sure there are other fun scenarios that someone
will have to squirrel out.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>