arm64: dts: sdm845: Add gpu and gmu device nodes

Add the nodes to describe the Adreno GPU and GMU devices for sdm845.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
[bjorn: Added required gx power-domain]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Signed-off-by: Andy Gross <agross@kernel.org>