rdma_cm, sdp: bug fixes and some changes to APM logic

rdma_cm, sdp: bug fixes and some changes to APM logic

- We no longer rely on the private data buffer of the LAP/APR messages for passive side LID improvement.
    Instead, we use the protocol defined LID improvement APR error code.
    - Two paths are allocated on id creation to simplify code.
    - Various small bug fixes.
    - Added a missing ref_count get
    - Some code cleanup.
    - Important: rdma_enable_apm may be called only upon receiving RDMA_CM_ROUTE_RESOLVED event.
      This was done to break symmetry on failover and possibly on other occasions.

Signed-off-by: Nir Muchtar <nirm@voltaire.com>
Signed-off-by: Moni Shoua <monis@voltaire.com>
Signed-off-by: Amir Vadai <amirv@mellanox.co.il>