common: Drop flash.h from common header

Move this uncommon header out of the common header.

Fix up some style problems in flash.h while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/mpc8568mds/bcsr.c b/board/freescale/mpc8568mds/bcsr.c
index 28e2a94..b1e638a 100644
--- a/board/freescale/mpc8568mds/bcsr.c
+++ b/board/freescale/mpc8568mds/bcsr.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <flash.h>
 #include <asm/io.h>
 
 #include "bcsr.h"