Kconfig: Migrate BOARD_LATE_INIT to a select

This option should not really be user selectable.  Note that on PowerPC
we currently only need BOARD_LATE_INIT when CHAIN_OF_TRUST is enabled so be
conditional on that.

Signed-off-by: Tom Rini <trini@konsulko.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com> (for UniPhier)
diff --git a/arch/Kconfig b/arch/Kconfig
index ffc7b45..bb1a818 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -60,6 +60,7 @@
 
 config SANDBOX
 	bool "Sandbox"
+	select BOARD_LATE_INIT
 	select SUPPORT_OF_CONTROL
 	select DM
 	select DM_KEYBOARD