Fix the issue where some Rx features cannot be changed.

When using ethtool -K to turn off rx offload, it returns error and
displays "Could not change any device features". And netdev->features
is not assigned a new value to actually configure the hardware.

Fixes: 6dbedcff ("net: libwx: Implement xx_set_features ops")
Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>