arm64: dts: imx93-tqma9352-mba93xxla: enable Open Drain for MDIO

The board has a pull-up resistor for MDIO pin per PHY design guide.
When MDIO is idle, it needs to be high and open drain is better
to be used here for power saving.

Signed-off-by: Markus Niebel <Markus.Niebel@ew.tq-group.com>
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>