kwbimage.c: Fix compile warning when building on 64 bit systems

Fix this warning when building on 64 bit systems:
tools/kwbimage.c: In function 'kwbimage_checksum32':
tools/kwbimage.c:135: warning: format '%d' expects type 'int',
but argument 4 has type 'long unsigned int'

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Prafulla Wadaskar <prafulla@marvell.com>

tools/kwbimage.c

@@ -131,7 +131,7 @@ static uint32_t kwbimage_checksum32 (uint32_t *start, uint32_t len, uint32_t csu
 		return 0;
 
 	if (len % sizeof(uint32_t)) {
-		printf ("Error:%s[%d] - lenght is not in multiple of %d\n",
+		printf ("Error:%s[%d] - lenght is not in multiple of %ld\n",
 			__FUNCTION__, len, sizeof(uint32_t));
 		return 0;
 	}