[ofw] winverbs ND provider

[Sean Hefty]

>> This is no different than the IBAL provider, though.
>
>For the ibal nd provider you are correct. For the normal ibal verbs
>this
>is not correct.
>The good old ibal has managed to do arm without going from user to
>kernel.

I think this is misleading.  IBAL makes use of separate threads that
drop into the kernel as part of its completion/event processing.

- Sean