arm64: dts: imx8mp: Enable gpu passive throttling

arm64: dts: imx8mp: Enable gpu passive throttling

Hook up the gpu as a passive cooling device to the thermal zones' alert
trip point just like the cpu.

The gpu here consists of 3D GPU, 2D GPU and NPU.

One way to test would be to set one "alert" trip point low enough
and watch the cooling device state increase:

echo 10000 > /sys/class/thermal/thermal_zone0/trip_point_0_temp
watch cat /sys/class/thermal/cooling_device*/cur_state

And of course set the trip point back to its original value and watch
the cooling device states jump to 0 again.

Signed-off-by: Martin Kepplinger-Novaković <martink@posteo.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>