arm64: dts: Add BRCM IPROC NAND DT node for NS2

The NAND controller on NS2 SoC is compatible with existing
BRCM IPROC NAND driver so let's enable it in NS2 DT and
NS2 SVK DT.

This patch also fixes use of node labels in ns2-svk.dts.

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Reviewed-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>