[new uImage] Make node unit names const in struct bootm_headers

Signed-off-by: Marian Balakowicz <m8@semihalf.com>

include/image.h

@@ -200,14 +200,14 @@ typedef struct bootm_headers {
 
 #if defined(CONFIG_FIT)
 	void		*fit_hdr_os;	/* os FIT image header */
-	char		*fit_uname_os;	/* os subimage node unit name */
+	const char	*fit_uname_os;	/* os subimage node unit name */
 
 	void		*fit_hdr_rd;	/* init ramdisk FIT image header */
-	char		*fit_uname_rd;	/* init ramdisk node unit name */
+	const char	*fit_uname_rd;	/* init ramdisk node unit name */
 
 #if defined(CONFIG_PPC)
 	void		*fit_hdr_fdt;	/* FDT blob FIT image header */
-	char		*fit_uname_fdt;	/* FDT blob node unit name */
+	const char	*fit_uname_fdt;	/* FDT blob node unit name */
 #endif
 	int		verify;		/* getenv("verify")[0] != 'n' */
 	int		autostart;	/* getenv("autostart")[0] != 'n' */