IB/cma: Refactor RDMA IP CM private-data parsing code

When receiving a connection request, rdma_cm needs to associate the request
with a network device, in order to disambiguate requests. To do this, it
needs to know the request's destination IP. For this the module needs to
allow getting this information from the private data in the request packet,
instead of relying on the information already being in the listening RDMA
CM ID.

When creating a new incoming connection ID, the code in
cma_save_ip{4,6}_info can no longer rely on the listener's private data to
find the port number, so it reads it from the requested service ID.

Signed-off-by: Guy Shapiro <guysh@mellanox.com>
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Yotam Kenneth <yotamke@mellanox.com>
Signed-off-by: Shachar Raindel <raindel@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>