ethtool: set EEE settings with EEE_SET request

Implement EEE_SET netlink request to set EEE settings of a network device.
These are traditionally set with ETHTOOL_SEEE ioctl request.

The netlink interface allows setting the EEE status for all link modes
supported by kernel but only first 32 link modes can be set at the moment
as only those are supported by the ethtool_ops callback.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>