net: mvpp2: cls: Invalidate all C2 entries except the ones we use

C2 TCAM entries can be invalidated to avoid unwanted matches. Make sure
all entries are invalidated at init, then validate only the ones we use.

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