ARM: DT: tegra: Unify the description of Tegra20 boards

Use engineering name 'Tegra20' instead of 'Tegra2'
Signed-off-by: NBryan Wu <pengw@nvidia.com>
Signed-off-by: NStephen Warren <swarren@nvidia.com>

arch/arm/boot/dts/tegra20-harmony.dts

@@ -3,7 +3,7 @@
 /include/ "tegra20.dtsi"
 
 / {
-	model = "NVIDIA Tegra2 Harmony evaluation board";
+	model = "NVIDIA Tegra20 Harmony evaluation board";
 	compatible = "nvidia,harmony", "nvidia,tegra20";
 
 	memory {

arch/arm/boot/dts/tegra20-ventana.dts

@@ -3,7 +3,7 @@
 /include/ "tegra20.dtsi"
 
 / {
-	model = "NVIDIA Tegra2 Ventana evaluation board";
+	model = "NVIDIA Tegra20 Ventana evaluation board";
 	compatible = "nvidia,ventana", "nvidia,tegra20";
 
 	memory {

arch/arm/boot/dts/tegra20-whistler.dts

@@ -3,7 +3,7 @@
 /include/ "tegra20.dtsi"
 
 / {
-	model = "NVIDIA Tegra2 Whistler evaluation board";
+	model = "NVIDIA Tegra20 Whistler evaluation board";
 	compatible = "nvidia,whistler", "nvidia,tegra20";
 
 	memory {