net: ethoc: Remove unnecessary #ifdef CONFIG_OF

For !CONFIG_OF of_get_property() is defined to always return NULL. Thus
there's no need to protect the call to of_get_property() with #ifdef
CONFIG_OF.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>