net/mlx5e: Add data path for SHAMPO feature

The header buffer is used to store the headers of the rx packets.
The header buffer size deduced from WorkQueue size + restriction
of max packets per WorkQueueElement.
This commit adds the functionality for posting/updating memory for
the header buffer during the posting/updating of WQEs.

Signed-off-by: Ben Ben-Ishay <benishay@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>