net: phy: hook up clause 45 autonegotiation restart

genphy_restart_aneg() can only restart autonegotiation on clause 22
PHYs.  Add a phy_restart_aneg() function which selects between the
clause 22 and clause 45 restart functionality depending on the PHY
type and whether the Clause 45 PHY supports the Clause 22 register set.

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