RDMA/cma: Override default responder_resources with user value

By default, the responder_resources parameter is set to that received
in a connection request.  The passive side may override this value
when accepting the connection.  Use the value provided by the passive
side when transitioning the QP to RTR state, rather than the value
given in the connect request.  Without this change, the RTR transition
may fail if the passive side supports fewer responder_resources than
that in the request.

For code consistency and to protect against QP destruction, restructure
overriding initiator_depth to match how responder_resources is set.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>