arm64: dts: NS2: Add USB DRD PHY device tree node

This patch adds device tree node for USB Dual Role Device PHY for
Broadcom's Northstar2 SoC.

Signed-off-by: Raviteja Garimella <raviteja.garimella@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>