net: phylink: only restart AN if the link mode is using in-band AN

If we are not using in-band autonegotiation, there is no point passing
the request to restart autonegotiation on to the driver.

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>