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/drivers/timer/cadence-ttc.c b/drivers/timer/cadence-ttc.c
index ed48a14..4837b06 100644
--- a/drivers/timer/cadence-ttc.c
+++ b/drivers/timer/cadence-ttc.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <bootstage.h>
 #include <dm.h>
 #include <errno.h>
 #include <timer.h>