common: Drop bootstage.h from common header

Move this fairly uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/cpu/apollolake/fsp_s.c b/arch/x86/cpu/apollolake/fsp_s.c
index 7ef169b..fd6e73d 100644
--- a/arch/x86/cpu/apollolake/fsp_s.c
+++ b/arch/x86/cpu/apollolake/fsp_s.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <binman.h>
+#include <bootstage.h>
 #include <dm.h>
 #include <irq.h>
 #include <malloc.h>