arm/tegra: rename board-dt.c to board-dt-tegra20.c

Tegra20 based boards will be handled by the current board-dt.c file. Tegra30
based boards will be handled by a new board-dt-tegra30.c file. Hence rename
the existing board-dt.c to board-dt-tegra20.c to reflect its use.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Colin Cross <ccross@android.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index 2b1d49b..996828d 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -57,10 +57,10 @@
 	 have large similarities with the seaboard design.
 
 config MACH_TEGRA_DT
-	bool "Generic Tegra board (FDT support)"
+	bool "Generic Tegra20 board (FDT support)"
 	select USE_OF
 	help
-	  Support for generic nVidia Tegra boards using Flattened Device Tree
+	  Support for generic NVIDIA Tegra20 boards using Flattened Device Tree
 
 config MACH_TRIMSLICE
        bool "TrimSlice board"