net/mlx5: share Memory Regions for multiport device

net/mlx5: share Memory Regions for multiport device

The multiport Infiniband device support was introduced [1].
All active ports, belonging to the same Infiniband device use the single
shared Infiniband context of that device and share the resources:
  - QPs are created within shared context
  - Verbs flows are also created with specifying port index
  - DV/DR resources
  - Protection Domain
  - Event Handlers

This patchset adds support for Memory Regions sharing between
ports, created on the base of multiport Infiniband device.
The datapath of mlx5 uses the layered cache subsystem for
allocating/releasing Memory Regions, only the lowest layer L3
is subject to share due to performance issues.

[1] http://patches.dpdk.org/cover/51800/

Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Acked-by: Yongseok Koh <yskoh@mellanox.com>