net: phy: add missing phy driver features

The phy drivers for CS4340 and TN2020 are missing their
features attributes. Add them.

Fixes: 719655a1 ("net: phy: Replace phy driver features u32 with link_mode bitmap")
Reported-by: Scott Wood <oss@buserror.net>
Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>