Using ethtool, users can specify a classification action matching on the
full vlan tag, which includes the DEI bit (also previously called CFI).

However, when converting the ethool_flow_spec to a flow_rule, we use
dissector keys to represent the matching patterns.

Since the vlan dissector key doesn't include the DEI bit, this
information was silently discarded when translating the ethtool
flow spec in to a flow_rule.

This commit adds the DEI bit into the vlan dissector key, and allows
propagating the information to the driver when parsing the ethtool flow
spec.

Fixes: eca4205f ("ethtool: add ethtool_rx_flow_spec to flow_rule structure translator")
Reported-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>