net: mvpp2: fix a typo in the RSS code

Cosmetic patch fixing a typo in one of the RSS comments.

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