The codes add ethtool functions to set RX flows for HW LRO. Because the
HW LRO hardware can only recognize the destination IP of TCP/IP RX flows,
the ethtool command to add HW LRO flow is as below:
ethtool -N [devname] flow-type tcp4 dst-ip [ip_addr] loc [0~1]

Otherwise, cause the hardware can set total four destination IPs, each
GMAC (GMAC1/GMAC2) can set two IPs separately at most.
Signed-off-by: Nelson Chang <nelson.chang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>