arm64: dts: Add SBA-RAID DT nodes for Stingray SoC

This patch adds Broadcom SBA-RAID DT nodes for Stingray SoC.

The Stingray SoC has total 32 SBA-RAID FlexRM rings and it has
8 CPUs so we create 8 SBA-RAID instances (one for each CPU).
This way Linux DMAENGINE will have one SBA-RAID DMA device for
each CPU.

Signed-off-by: Anup Patel <anup.patel@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>