FDT: don't use private kernel header files

On some systems (for example Fedora Core 4) U-Boot builds with the
following wanrings only:

...
In file included from /home/wd/git/u-boot/include/libfdt_env.h:33,
                 from fdt.c:51:
		 /usr/include/asm/byteorder.h:6:2: warning: #warning using private kernel header; include <endian.h> instead!

This patch fixes this problem.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/include/image.h b/include/image.h
index 82e6345..1598b61 100644
--- a/include/image.h
+++ b/include/image.h
@@ -33,27 +33,29 @@
 #ifndef __IMAGE_H__
 #define __IMAGE_H__
 
-#include <asm/byteorder.h>
-#include <command.h>
-
-#ifndef USE_HOSTCC
-#include <lmb.h>
-#include <linux/string.h>
-#include <asm/u-boot.h>
-
-#else
+#if USE_HOSTCC
+#include <endian.h>
 
 /* new uImage format support enabled on host */
 #define CONFIG_FIT		1
 #define CONFIG_OF_LIBFDT	1
 #define CONFIG_FIT_VERBOSE	1 /* enable fit_format_{error,warning}() */
 
+#else
+
+#include <lmb.h>
+#include <linux/string.h>
+#include <asm/u-boot.h>
+#include <asm/byteorder.h>
+
 #endif /* USE_HOSTCC */
 
 #if defined(CONFIG_FIT) && !defined(CONFIG_OF_LIBFDT)
 #error "CONFIG_OF_LIBFDT not enabled, required by CONFIG_FIT!"
 #endif
 
+#include <command.h>
+
 #if defined(CONFIG_FIT)
 #include <fdt.h>
 #include <libfdt.h>