RDMA/cxgb3: Fix stack info leak in iwch_create_cq()

The "uresp.reserved" field isn't initialized on this path so it could
leak uninitialized stack information to the user.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>