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/common/spl/spl_xip.c b/common/spl/spl_xip.c
index 1af4da8..f857278 100644
--- a/common/spl/spl_xip.c
+++ b/common/spl/spl_xip.c
@@ -5,6 +5,7 @@
  */
 
 #include <common.h>
+#include <image.h>
 #include <spl.h>
 
 static int spl_xip(struct spl_image_info *spl_image,