mvneta: recycle buffers

mvneta: recycle buffers

Use the new recycling API for page_pool.
In a drop rate test, the packet rate increased by 10%,
from 296 Kpps to 326 Kpps.

perf top on a stock system shows:

Overhead  Shared Object     Symbol
  23.66%  [kernel]          [k] __pi___inval_dcache_area
  22.85%  [mvneta]          [k] mvneta_rx_swbm
   7.54%  [kernel]          [k] kmem_cache_alloc
   6.49%  [kernel]          [k] eth_type_trans
   3.94%  [kernel]          [k] dev_gro_receive
   3.91%  [kernel]          [k] __netif_receive_skb_core
   3.91%  [kernel]          [k] kmem_cache_free
   3.76%  [kernel]          [k] page_pool_release_page
   3.56%  [kernel]          [k] free_unref_page
   2.40%  [kernel]          [k] build_skb
   1.49%  [kernel]          [k] skb_release_data
   1.45%  [kernel]          [k] __alloc_pages_bulk
   1.30%  [kernel]          [k] page_frag_free

And this is the same output with recycling enabled:

Overhead  Shared Object     Symbol
  26.41%  [kernel]          [k] __pi___inval_dcache_area
  25.00%  [mvneta]          [k] mvneta_rx_swbm
   8.14%  [kernel]          [k] kmem_cache_alloc
   6.84%  [kernel]          [k] eth_type_trans
   4.44%  [kernel]          [k] __netif_receive_skb_core
   4.38%  [kernel]          [k] kmem_cache_free
   4.16%  [kernel]          [k] dev_gro_receive
   3.21%  [kernel]          [k] page_pool_put_page
   2.41%  [kernel]          [k] build_skb
   1.82%  [kernel]          [k] skb_release_data
   1.61%  [kernel]          [k] napi_gro_receive
   1.25%  [kernel]          [k] page_pool_refill_alloc_cache
   1.16%  [kernel]          [k] __netif_receive_skb_list_core

We can see that page_pool_release_page(), free_unref_page() and
__alloc_pages_bulk() are no longer on top of the list when receiving
traffic.

The test was done with mausezahn on the TX side with 64 byte raw
ethernet frames.

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>