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/image-fit.c b/common/image-fit.c
index 368b730..dc745fe 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -11,6 +11,7 @@
 #ifdef USE_HOSTCC
 #include "mkimage.h"
 #include <time.h>
+#include <linux/libfdt.h>
 #include <u-boot/crc.h>
 #else
 #include <linux/compiler.h>