net: Fix dev dev_ethtool_get_rx_csum() for forced NETIF_F_RXCSUM

dev_ethtool_get_rx_csum() won't report rx checksumming when it's not
changeable and driver is converted to hw_features and friends. Fix this.

(dev->hw_features & NETIF_F_RXCSUM) check is dropped - if the
ethtool_ops->get_rx_csum is set, then driver is not coverted, yet.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>