net: mvpp2: make multi queue mode the default mode

The multi queue mode is needed to have RSS available, and offers some
nice advantages, being able to have one rx queue vector per CPU.

This mode has been usable through the use of a module parameter, this
commit makes it the default value.

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