arm64: dts: qcom: sa8775p: add the GPU IOMMU node

Add the Adreno GPU IOMMU for sa8775p-based platforms.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230417125844.400782-6-brgl@bgdev.pl