Document the missing sfp property for ethernet controllers (which
has existed for some time) which is being extended to ethernet PHYs.
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: NRob Herring <robh@kernel.org>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>