arm64: dts: Add IPROC RNG200 DT node for NS2

We have IPROC RNG200 hardware random number generation in
NS2 SoC, lets enable it for NS2 in NS2 DT.

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Pramod KUMAR <pramodku@broadcom.com>
Reviewed-by: Vikram Prakash <vikramp@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>