net/mlx5e: RX, Remove unnecessary recycle parameter and page_cache stats

net/mlx5e: RX, Remove unnecessary recycle parameter and page_cache stats

The recycle parameter used during page release is no longer
necessary: the page pool can detect when the page cannot be
recycled to the cache or ring without any outside hint.

The page pool will also take care of cleaning up after itself
once all the inflight pages have been released. So no need to
explicitly release pages to the system.

Remove the internal page_cache stats as the mlx5e_page_cache
struct no longer exists.

Delete the documentation entries along with the stats.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>