new-image: Fix host tool build breakage

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>

include/fdt.h

@@ -3,6 +3,10 @@
 
 #ifndef __ASSEMBLY__
 
+#ifdef USE_HOSTCC
+#include <stdint.h>
+#endif
+
 struct fdt_header {
 	uint32_t magic;			 /* magic word FDT_MAGIC */
 	uint32_t totalsize;		 /* total size of DT block */