cpu/mpc512x/diu.c: fix warning: assignment from incompatible pointer type

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: John Rigby <jcrigby@gmail.com>
diff --git a/cpu/mpc512x/diu.c b/cpu/mpc512x/diu.c
index 6d7e40f..70849ee 100644
--- a/cpu/mpc512x/diu.c
+++ b/cpu/mpc512x/diu.c
@@ -95,7 +95,7 @@
 		bmp = valid_bmp(bmp_env);
 	}
 	if (!bmp)
-		bmp = FSL_Logo_BMP;
+		bmp = (char *)FSL_Logo_BMP;
 	return fsl_diu_init(xres, pixel_format, 0, (unsigned char *)bmp);
 }