net: fec: Fix issue in DM probe timeout

Since the probe function has changed to reset FEC controller prior than
setup PHY. If reset FEC controller timeout, the priv->phydev is not
initialized, so can't free it.

Signed-off-by: Ye Li <ye.li@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>