drivers: net: fsl_enetc: set phydev->node

The saved ofnode is used by some PHY drivers to access the device tree
node of the PHY.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Alex Marginean <alexm.osslist@gmail.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>