treewide: Migrate CONFIG_LAST_STAGE_INIT to Kconfig

Migrate the CONFIG_LAST_STAGE_INIT option to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/common/Kconfig b/common/Kconfig
index f09e77d..5c90ce4 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -602,6 +602,15 @@
 	  relocation. With this option, U-Boot calls board_early_init_r()
 	  in the post-relocation init sequence.
 
+config LAST_STAGE_INIT
+	bool "Call board-specific as last setup step"
+	help
+	  Some boards need to perform initialisation immediately before control
+	  is passed to the command-line interpreter (e.g. for initializations
+	  that depend on later phases in the init sequence). With this option,
+	  U-Boot calls last_stage_init() before the command-line interpreter is
+	  started.
+
 endmenu
 
 menu "Security support"