bnx2x, cnic: Consolidate iSCSI/FCoE shared mem logic in bnx2x

Move all shared mem code to bnx2x to avoid code duplication.  bnx2x now
performs:

- Read the FCoE and iSCSI max connection information.
- Read the iSCSI and FCoE MACs from NPAR configuration in shmem.
- Block the CNIC for the current function if there is neither FCoE nor
  iSCSI valid configuration by returning NULL from bnx2x_cnic_probe().

Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>