net: bcmgenet: add support for ethtool rxnfc flows

This commit enables driver support for ethtool commands of this form:
ethtool -N|-U|--config-nfc|--config-ntuple devname
    flow-type ether|ip4
    [src xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]]
    [dst xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]] [proto N [m N]]
    [src-ip x.x.x.x [m x.x.x.x]] [dst-ip x.x.x.x [m x.x.x.x]] [tos N [m N]]
    [l4proto N [m N]] [src-port N [m N]] [dst-port N [m N]] [spi N [m N]]
    [l4data N [m N]] [vlan-etype N [m N]] [vlan N [m N]]
    [dst-mac xx:yy:zz:aa:bb:cc [m xx:yy:zz:aa:bb:cc]] [action 0] [loc N] |
    delete N

Since there is only one Rx Ring in this implementation action 0 behaves no
differently from not specifying a rule.

The rules can be seen with ethtool commands of this form:
ethtool -n|-u|--show-nfc|--show-ntuple devname [rule N]

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>