ARM: tegra: Add IOMMU node to GK20A

Nouveau can make use of the IOMMU to make physical appear linear in the
GPU address space.
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra124.dtsi

@@ -189,6 +189,9 @@ gpu@0,57000000 {
 		clock-names = "gpu", "pwr";
 		resets = <&tegra_car 184>;
 		reset-names = "gpu";
+
+		iommus = <&mc TEGRA_SWGROUP_GPU>;
+
 		status = "disabled";
 	};