arm64: dts: NS2: Add PCI PHYs

PCI PHYs are missing from the Northstar2 DT entries for the 2 PCI buses.
Add them so that PCI devices can be discovered.

Signed-off-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>