regex/mlx5: fix memory region unregistration

regex/mlx5: fix memory region unregistration

The issue can cause illegal physical address access while a huge-page A
is released and huge-page B is allocated on the same virtual address.
The old MR can be matched using the virtual address of huge-page B but
the HW will access the physical address of huge-page A which is no more
part of the DPDK process.

Register a driver callback for memory event in order to free out all the
MRs of memory that is going to be freed from the DPDK process.

Fixes: cda883bbb655 ("regex/mlx5: add dynamic memory registration to datapath")
Cc: stable@dpdk.org
Signed-off-by: Michael Baum <michaelba@nvidia.com>
Acked-by: Ori Kam <orika@nvidia.com>