arm: mvebu: add L2 cache support

arm: mvebu: add L2 cache support

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-and-reviewed-by: Yehuda Yitschak <yehuday@marvell.com>
Tested-and-reviewed-by: Lior Amsalem <alior@marvell.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>