net/mlx5e: Rename mlx5e_dma_info to prepare for removal of DMA address

The next commit will remove the DMA address from the struct currently
called mlx5e_dma_info, because the same value can be retrieved with
page_pool_get_dma_addr(page) in almost all cases, with the notable
exception of SHAMPO (HW GRO implementation) that modifies this address
on the fly, after the initial allocation.

To keep the SHAMPO logic intact, struct mlx5e_dma_info remains in the
SHAMPO code, consisting of addr and page (XSK is not compatible with
SHAMPO). The struct used in all other places is renamed to
mlx5e_alloc_unit, allowing the next commit to remove the addr field
without affecting SHAMPO.

The new name means "allocation unit", and it's more appropriate after
the field with the DMA address gets removed.

Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>