net/mlx5: fs, add mlx5_fs_pool API

net/mlx5: fs, add mlx5_fs_pool API

Refactor fc_pool API to create generic fs_pool API, as HW steering has
more flow steering elements which can take advantage of the same pool of
bulks API. Change fs_counters code to use the fs_pool API.

Note, removed __counted_by from struct mlx5_fc_bulk as bulk_len is now
inner struct member. It will be added back once __counted_by can support
inner struct members.

Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/20241219175841.1094544-5-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>