ARM: Add Tauros2 L2 cache controller support

Support for the Tauros2 L2 cache controller as used with the PJ1
and PJ4 CPUs.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>