config: enable PHYLIB=y and ETHTOOL_NETLINK=y
    
    As an unfortunate side effect of ethtool cable diagnostic support,
    ETHTOOL_NETLINK now depends on PHYLIB and the dependency is implemented in
    a way making "make oldconfig" drops ETHTOOL_NETLINK if PHYLIB=m.
    
    Until this issue is resolved in upstream, set PHYLIB=y so that
    ETHTOOL_NETLINK can be enabled again.