[ofw] proposed UVP change to support CQ polling

[Sean Hefty]

Basically, I'd like to expose UVP functionality that's already there...

I propose adding a new function to uvp_interface_t that can be used to return QP
context information with work completions:

int uvp_poll_cq_array(struct ibv_cq *cq, struct _uvp_wc *wc, int entries);

struct _uvp_wc
{
	void *qp_context;
	struct _ib_wc wc;
};

This would map to mthca_poll_cq(), which is implemented, but I don't think is
used or exposed.  (This should give minimal code changes - about 20 lines total.
If people are okay with a slightly larger change, we can match uvp_wc up with
WV_COMPLETION instead of ib_wc.) 

Separate from this, I think WinVerbs CQ::Poll() should change from 

Poll(WV_COMPLETION* pCompletions[], SIZE_T Entries)
to
Poll(WV_COMPLETION Completions[], SIZE_T Entries)

Comments on either of the above changes?

- Sean