ethtool: add WOL_NTF notification

Send ETHTOOL_MSG_WOL_NTF notification whenever wake-on-lan settings of
a device are modified using ETHTOOL_MSG_WOL_SET netlink message or
ETHTOOL_SWOL ioctl request.

As notifications can be received by anyone, do not include SecureOn(tm)
password in notification messages.

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