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.