net: mvpp2: fix missing switch case break

Signed-off-by: Ben Peled <bpeled@marvell.com>
Reviewed-by: Stefan Chulski <stefanc@marvell.com>
Reviewed-by: Kostya Porotchkin <kostap@marvell.com>
Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>