net/mlx5e: TC, Add sampler object API

In order to offload sample action, HW introduces sampler object. The
sampler object samples packets according to the provided sample ratio.
Sampled packets are duplicated. One copy is processed by a termination
table, named the sample table, which sends the packet up to software.
The second copy is processed by the default table.

Instantiate sampler object. Re-use identical sampler object for
the same sample ratio, sample table and default table as a prestep for
offloading tc sample actions.

Signed-off-by: Chris Mi <cmi@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>