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_spi.c b/common/spl/spl_spi.c
index 288dbb5..7a374bb 100644
--- a/common/spl/spl_spi.c
+++ b/common/spl/spl_spi.c
@@ -9,6 +9,7 @@
  */
 
 #include <common.h>
+#include <image.h>
 #include <spi.h>
 #include <spi_flash.h>
 #include <errno.h>