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/lib/fsp2/fsp_init.c b/arch/x86/lib/fsp2/fsp_init.c
index c7dc2ea..008e8ae 100644
--- a/arch/x86/lib/fsp2/fsp_init.c
+++ b/arch/x86/lib/fsp2/fsp_init.c
@@ -6,6 +6,7 @@
 #include <common.h>
 #include <binman.h>
 #include <binman_sym.h>
+#include <bootstage.h>
 #include <cbfs.h>
 #include <dm.h>
 #include <init.h>