[ewg] broken support for UC in rdma_cm

[Eli Cohen]

We got failing tests in our regression that use UC transport from
userspace. Looking at cma_connect_ib(), I see that it uses IB_QPT_RC
in the CM request instead of using whatever the transport type of the
requesting QP. There is no easy way to retrieve that information too
since the QP is created in userspace. We do have the QP number. One
way to address this problem is to have an API that returns a pointer
to struct ib_qp given the ib device and the QP number. Another way
would be to pass qp_type through the call to rdma_init_qp_attr().
Thoughts?