mpc5121: cpu/mpc512x/diu.c: fix warnings

Fix warnings while compiling with CONFIG_VIDEO enabled:

diu.c: In function 'video_hw_init':
diu.c:158: warning: 'return' with no value, in function returning non-void
diu.c:162: warning: format '%ld' expects type 'long int', but argument 6 has type 'int'
diu.c:162: warning: format '%ld' expects type 'long int', but argument 7 has type 'int'

Signed-off-by: Anatolij Gustschin <agust@denx.de>

cpu/mpc512x/diu.c

@@ -145,10 +145,10 @@ void *video_hw_init(void)
 	struct fb_info *info;
 
 	if (mpc5121_diu_init() < 0)
-		return;
+		return NULL;
 
 	/* fill in Graphic device struct */
-	sprintf(pGD->modeIdent, "%dx%dx%d %ldkHz %ldHz",
+	sprintf(pGD->modeIdent, "%dx%dx%d %dkHz %dHz",
 		xres, yres, 32, 64, 60);
 
 	pGD->frameAdrs = (unsigned int)fsl_fb_open(&info);