net/mlx5: support upstream rdma-core

net/mlx5: support upstream rdma-core

This removes the dependency on specific Mellanox OFED libraries by
using the upstream rdma-core and linux upstream community code.
Both rdma-core upstream and Mellanox OFED are Linux user-space packages:
  1. Rdma-core is Linux upstream user-space package.(Generic)
  2. Mellanox OFED is Mellanox's Linux user-space package.(Proprietary)
The difference between the two are the APIs towards the kernel.

Support for x86-32 is removed due to issues in rdma-core library.
ICC compilation will be supported as soon as the following patch is
integrated in rdma-core:
https://marc.info/?l=linux-rdma&m=150643474705690&w=2

Signed-off-by: Shachar Beiser <shacharbe@mellanox.com>
Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>