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>

cmd/jffs2.c

@@ -73,6 +73,7 @@
 #include <common.h>
 #include <command.h>
 #include <env.h>
+#include <flash.h>
 #include <image.h>
 #include <malloc.h>
 #include <jffs2/jffs2.h>