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/board/engicam/common/spl.c b/board/engicam/common/spl.c
index a9820a9..6359fb3 100644
--- a/board/engicam/common/spl.c
+++ b/board/engicam/common/spl.c
@@ -6,6 +6,7 @@
  */
 
 #include <common.h>
+#include <image.h>
 #include <serial.h>
 #include <spl.h>