net: ethernet: ti: am65-cpsw: use napi_complete_done() in TX completion

net: ethernet: ti: am65-cpsw: use napi_complete_done() in TX completion

This patch enables support for hard irqs deferral feature from Eric Dumazet
[1] for TI K3 CPSW driver by using napi_complete_done() in TX completion
path.

Depending on gro_flush_timeout and napi_defer_hard_irqs at gives up to 30%
CPU utilization reduction:

gro_flush_timeout=50000
napi_defer_hard_irqs=2

netperf -l 10 -H 192.168.1.1  -t UDP_STREAM -c -C -- -m 1470
MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.1.1 () port 0 AF_INET
Socket  Message  Elapsed      Messages                   CPU      Service
Size    Size     Time         Okay Errors   Throughput   Util     Demand
bytes   bytes    secs            #      #   10^6bits/sec % SS     us/KB

before:
212992    1470   10.00      809632      0      952.0     42.98    14.792
212992           10.00      809630             952.0     50.66    8.719

after:
212992    1470   10.00      813686      0      956.8     32.14    11.009
212992           10.00      813686             956.8     50.05    8.570

[1] https://lore.kernel.org/netdev/20200422161329.56026-1-edumazet@google.com/

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>