net: sfp: move phy_start()/phy_stop() to phylink

Move phy_start() and phy_stop() into the module_start and module_stop
notifications in phylink, rather than having them in the SFP code.
This gives phylink responsibility for controlling the PHY, rather
than having SFP start and stop the PHY state machine.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>