Convert CONFIG_SPL_BOARD_INIT to Kconfig

This converts the following to Kconfig:
   CONFIG_SPL_BOARD_INIT

Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
[trini: Update the Kconfig logic]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index c67ffa5..66cf960 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -49,6 +49,7 @@
 	bool "Tegra 32-bit common options"
 	select CPU_V7
 	select SPL
+	select SPL_BOARD_INIT if SPL
 	select SUPPORT_SPL
 	select TEGRA_COMMON
 	select TEGRA_GPIO