i40e: Add Energy Efficient Ethernet ability for X710 Base-T/KR/KX cards

Add "EEE: Enabled/Disabled" to dmesg for supported X710 Base-T/KR/KX
cards. According to the IEEE standard report the EEE ability and the
EEE Link Partner ability. Use the kernel's 'ethtool_keee' structure
and report EEE link modes.

Example:
dmesg | grep 'NIC Link is'
ethtool --show-eee <device>

Before:
	NIC Link is Up, 10 Gbps Full Duplex, Flow Control: None

        Supported EEE link modes:  Not reported
        Advertised EEE link modes:  Not reported
        Link partner advertised EEE link modes:  Not reported

After:
	NIC Link is Up, 10 Gbps Full Duplex, Flow Control: None, EEE: Enabled

        Supported EEE link modes:  100baseT/Full
                                   1000baseT/Full
                                   10000baseT/Full
        Advertised EEE link modes:  100baseT/Full
                                    1000baseT/Full
                                    10000baseT/Full
        Link partner advertised EEE link modes:  100baseT/Full
                                                 1000baseT/Full
                                                 10000baseT/Full

Reviewed-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>