Merge branch 'vlan_offloads'

Vlad Yasevich says:

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Audit all drivers for correct vlan_features.

Some drivers set vlan acceleration features in vlan_features.  This causes
issues with Q-in-Q/802.1ad configurations.

Audit all the drivers for correct vlan_features.  Fix broken ones.
Add a warning to vlan code to help catch future offenders.
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Signed-off-by: David S. Miller <davem@davemloft.net>