arm64: dts: stingray: add bcm958802a802x dts

Add bcm958802a802x dts to be used on all Stingray smart NIC PS225 board
variants

Signed-off-by: Vladimir Olovyannikov <vladimir.olovyannikov@broadcom.com>
Signed-off-by: Pramod Kumar <pramod.kumar@broadcom.com>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>