ARM: tegra: Add device tree node to describe IRAM on Tegra20

All Tegra20 SoCs contain 256 KiB IRAM, which is used to store resume
code and by the video decoder engine.
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/boot/dts/tegra20.dtsi

@@ -10,6 +10,14 @@ / {
 	compatible = "nvidia,tegra20";
 	interrupt-parent = <&lic>;
 
+	iram@40000000 {
+		compatible = "mmio-sram";
+		reg = <0x40000000 0x40000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x40000000 0x40000>;
+	};
+
 	host1x@50000000 {
 		compatible = "nvidia,tegra20-host1x", "simple-bus";
 		reg = <0x50000000 0x00024000>;