bcm63xx: batch process RX path

bcm63xx: batch process RX path

Use netif_receive_skb_list to batch process skb in RX.
Tested on BCM6328 320 MHz using iperf3 -M 512, increasing performance by 12.5%.

Before:
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-30.00  sec   120 MBytes  33.7 Mbits/sec  277             sender
[  4]   0.00-30.00  sec   120 MBytes  33.5 Mbits/sec                  receiver

After:
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-30.00  sec   136 MBytes  37.9 Mbits/sec  203             sender
[  4]   0.00-30.00  sec   135 MBytes  37.7 Mbits/sec                  receiver

Signed-off-by: Sieng Piaw Liew <liew.s.piaw@gmail.com>
[Amend commit description]
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>