ARM: NSP: Add basic support for Broadcom Northstar Plus SoC

Broadcom Northstar Plus family of SoCs are used for switching
control and management applications as well as residential
router/gateway applications. The SoC features dual core Cortex
A9 ARM CPUs, integrating several peripheral interfaces including
multiple Gigabit Ethernet PHYs, DDR3 memory, PCIE Gen-2, USB 2.0
and USB 3.0, serial and NAND flash, SATA and several other IO
controllers.

Signed-off-by: Kapil Hali <kapilh@broadcom.com>
Signed-off-by: Jon Mason <jonmason@broadcom.com>
Acked-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>