net/mlx4: support secondary process

net/mlx4: support secondary process

In order to support secondary process, a few features are required.

a) rdma-core library should allocate device resources using DPDK's
   memory allocator.

b) UAR should be remapped for secondary processes. Currently, in order
   not to use different data structure for secondary processes, PMD
   tries to reserve identical virtual address space for both primary
   and secondary processes.

c) IPC channel is necessary, which can be easily set with rte_mp APIs.
   Through the channel, Verbs command FD is delivered to the secondary
   process and the device stop/start event is also broadcast from
   primary process.

Signed-off-by: Yongseok Koh <yskoh@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>