net: mvpp2: cls: Add support for ETHER_FLOW

Users can specify classification actions based on the 'ether' flow type.
In that case, this will apply to all ethernet traffic, superseeding
flows such as 'udp4' or 'tcp6'.

Add support for this flow type in the PPv2 classifier, by mapping the
ETHER_FLOW value to the corresponding entries in the classifier.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>