tegra: kconfig: move board select menu and common settings

Becuase the board select menu in arch/arm/Kconfig is too big,
move the Tegra board select menu to tegra/Kconfig.

Insert the Tegra SoC select menu between the arch select and the
board select.

 Architecture select
 |-- Tegra Platform (Tegra)
     |- Tegra SoC select (Tegra20 / 30 / 114 / 124)
        |- Board select

Consolidate also common settings (CONFIG_SYS_CPU="armv7" and
CONFIG_SYS_SOC="tegra*") and always "select" CONFIG_SPL as follows:

  config TEGRA
          bool
          select SPL

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Cc: Tom Warren <twarren@nvidia.com>
diff --git a/arch/arm/cpu/armv7/tegra20/Kconfig b/arch/arm/cpu/armv7/tegra20/Kconfig
new file mode 100644
index 0000000..e2e0890
--- /dev/null
+++ b/arch/arm/cpu/armv7/tegra20/Kconfig
@@ -0,0 +1,53 @@
+if TEGRA20
+
+choice
+	prompt "Tegra20 board select"
+
+config TARGET_HARMONY
+	bool "NVIDIA Tegra20 Harmony evaluation board"
+
+config TARGET_MEDCOM_WIDE
+	bool "Avionic Design Medcom-Wide board"
+
+config TARGET_PAZ00
+	bool "Paz00 board"
+
+config TARGET_PLUTUX
+	bool "Avionic Design Plutux board"
+
+config TARGET_SEABOARD
+	bool "NVIDIA Seaboard"
+
+config TARGET_TEC
+	bool "Avionic Design Tamonten Evaluation Carrier"
+
+config TARGET_TRIMSLICE
+	bool "Compulab TrimSlice board"
+
+config TARGET_VENTANA
+	bool "NVIDIA Tegra20 Ventana evaluation board"
+
+config TARGET_WHISTLER
+	bool "NVIDIA Tegra20 Whistler evaluation board"
+
+config TARGET_COLIBRI_T20_IRIS
+	bool "Toradex Colibri T20 board"
+
+endchoice
+
+config SYS_SOC
+	string
+	default "tegra20"
+
+source "board/nvidia/harmony/Kconfig"
+source "board/avionic-design/medcom-wide/Kconfig"
+source "board/compal/paz00/Kconfig"
+source "board/avionic-design/plutux/Kconfig"
+source "board/nvidia/seaboard/Kconfig"
+source "board/avionic-design/tec/Kconfig"
+source "board/compulab/trimslice/Kconfig"
+source "board/nvidia/ventana/Kconfig"
+source "board/nvidia/whistler/Kconfig"
+source "board/toradex/colibri_t20_iris/Kconfig"
+
+endif