From: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Date: Sat,  7 May 2011 13:48:02 +0200 (CEST)

This moves checks that device is forwarding from bridge, IPv4 and IPv6
code into netdev_fix_features(). As a side effect, after device is no longer
forwarding it gets LRO back. This also means that user is not allowed to
enable LRO after device is put to forwarding mode.

This patch depends on removal of discrete offload setting ethtool ops.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>

We need to keep the check in the protocols because we don't want to
be testing protocol specific device state in generic code like
net/core/dev.c