common: Drop image.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/fdt.c b/cmd/fdt.c
index 36cc726..f66ceca 100644
--- a/cmd/fdt.c
+++ b/cmd/fdt.c
@@ -10,6 +10,7 @@
 #include <common.h>
 #include <command.h>
 #include <env.h>
+#include <image.h>
 #include <linux/ctype.h>
 #include <linux/types.h>
 #include <asm/global_data.h>