arm64: dts: Add NAND DT nodes for Stingray SOC

This patch adds NAND controller DT Node and NAND chip DT
node for Stingray SOC and Stingray reference boards.

Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
Signed-off-by: Abhishek Shah <abhishek.shah@broadcom.com>
Reviewed-by: Vikram Prakash <vikram.prakash@broadcom.com>
Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>