phylink: convert to fwnode

Convert phylink to fwnode, switching phylink_create() from taking a
device_node to taking a fwnode_handle. This will allow other firmware
systems to take advantage of sfp/phylink support.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>