ARM: dts: bcm2711: Enable V3D

This adds the entry for V3D for bcm2711 (used in the Raspberry Pi 4)
and the associated firmware clock entry.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>