[ewg] IB/ipoib: Fix neigh destructor oops for kernels older than 2.6.21

[Or Gerlitz]

Eli Cohen wrote:
> Unfortunately not. But I did not want to leave this problem pending
> anymore since I want to get some mileage on it. Still, if we have a
> better solution it would be easy to adopt since this patch is
> independent of all others.
>
>   
I see, next time, could you drop a mail saying that you decided to move 
on with something, etc?

Or.