[ofw] userspace rearm_cq

[Sean Hefty]

>For Network Direct, the UVP is not involved, the client's OVERLAPPED is used in
>an IOCTL to the kernel, where the CQ doorbell is rung and the IRP queued.  When
>the notification event occurs, the IRP is completed from the CQ's
>DISPATCH_LEVEL callback.

I ended up doing this differently in Winverbs.  It queues the overlapped in the
kernel to either an 'error queue' or a 'completion queue' associated with the
CQ.  If the IOCTL returns some for of success, then the library calls the uvp
rearm routine.  Functionally, I'm guessing these are roughly the same.

- Sean