ARM: dts: bcm283x: Use firmware PM driver for V3D

The register based driver turned out to be unstable, specially on RPi3a+
but not limited to it. While a fix is being worked on, we roll back to
using firmware based scheme.

Fixes: e1dc2b2e ("ARM: bcm283x: Switch V3D over to using the PM driver instead of firmware")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/20200303173217.3987-1-nsaenzjulienne@suse.de