net: sun4i-emac: remove erroneous assignment

The newly added sun4i-emac driver causes a build error when
CONFIG_NET_POLL_CONTROLLER is set, because it attempts to
assign a pointer to netdev->poll_controller, which has
been replaced with ops->ndo_poll_controller in 2.6.31!

The correct assignment is present as well, so we just need
to remove the wrong one.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Stefan Roese <sr@denx.de>
Acked-by: Maxime Ripard <maxime.ripard@anandra.org>
Signed-off-by: David S. Miller <davem@davemloft.net>