net: ibm: emac: use netif_receive_skb_list

net: ibm: emac: use netif_receive_skb_list

Small rx improvement. Would use napi_gro_receive instead but that's a
lot more involved than netif_receive_skb_list because of how the
function is implemented.

Before:

> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 51556 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   559 MBytes   467 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 48228 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.03 sec   558 MBytes   467 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 47600 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   557 MBytes   466 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 37252 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.05 sec   559 MBytes   467 Mbits/sec

After:

> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 40786 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.05 sec   572 MBytes   478 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 52482 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   571 MBytes   477 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 48370 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   572 MBytes   478 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 46086 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.05 sec   571 MBytes   476 Mbits/sec
> iperf -c 192.168.1.1
------------------------------------------------------------
Client connecting to 192.168.1.1, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.101 port 46062 connected with 192.168.1.1 port 5001
[ ID] Interval       Transfer     Bandwidth
[  1] 0.00-10.04 sec   572 MBytes   478 Mbits/sec

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>