net: phylink: simplify phy case for ksettings_set method

When we have a PHY attached, an ethtool ksettings_set() call only
really needs to call through to the phylib equivalent; phylib will
call back to us when the link changes so we can update our state.
Therefore, we can bypass most of our ksettings_set() call for this
case.

Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>