net: dsa: sja1105: add 100baseT1_Full support

Validate 100baseT1_Full to make this driver work with TJA1102 PHY.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Acked-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>