RDMA/mlx5: Allow DM allocation for sw_owner_v2 enabled devices

sw_owner_v2 will replace sw_owner for future devices, this means that if
sw_owner_v2 is set sw_owner should be ignored and DM allocation is
required for sw_owner_v2 devices to function.

Link: https://lore.kernel.org/r/20200903073857.1129166-3-leon@kernel.org


Signed-off-by: Alex Vesker <valex@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>