IB/mlx4: Add a driver Mellanox ConnectX InfiniBand adapters

Add an InfiniBand driver for Mellanox ConnectX adapters.  Because
these adapters can also be used as ethernet NICs and Fibre Channel
HBAs, the driver is split into two modules:

  mlx4_core: Handles low-level things like device initialization and
    processing firmware commands.  Also controls resource allocation
    so that the InfiniBand, ethernet and FC functions can share a
    device without stepping on each other.

  mlx4_ib: Handles InfiniBand-specific things; plugs into the
    InfiniBand midlayer.

Signed-off-by: Roland Dreier <rolandd@cisco.com>