arm64: dts: NS2: enable GICv2m for PAXB/PAXC interfaces

PAXB and PAXC PCIe interfaces on NS2 have been using the iProc event
queue to handle MSI. With the gicv2m support ready, we should now switch
to gicv2m for MSI handling

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