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/tegra-common/Kconfig b/arch/arm/cpu/armv7/tegra-common/Kconfig
new file mode 100644
index 0000000..8e2153b
--- /dev/null
+++ b/arch/arm/cpu/armv7/tegra-common/Kconfig
@@ -0,0 +1,30 @@
+if TEGRA
+
+choice
+	prompt "Tegra SoC select"
+
+config TEGRA20
+	bool "Tegra20 family"
+
+config TEGRA30
+	bool "Tegra30 family"
+
+config TEGRA114
+	bool "Tegra114 family"
+
+config TEGRA124
+	bool "Tegra124 family"
+
+endchoice
+
+config SYS_CPU
+	string
+	default "arm720t" if SPL_BUILD
+	default "armv7" if !SPL_BUILD
+
+source "arch/arm/cpu/armv7/tegra20/Kconfig"
+source "arch/arm/cpu/armv7/tegra30/Kconfig"
+source "arch/arm/cpu/armv7/tegra114/Kconfig"
+source "arch/arm/cpu/armv7/tegra124/Kconfig"
+
+endif