video: s3c-fb: return an error when bpp is invalid

This patch returns an error, when bpp is invalid in
s3c_fb_check_var(). If invalid bpp is requested,
an error should be returned.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>

drivers/video/s3c-fb.c

@@ -330,6 +330,7 @@ static int s3c_fb_check_var(struct fb_var_screeninfo *var,
 
 	default:
 		dev_err(sfb->dev, "invalid bpp\n");
+		return -EINVAL;
 	}
 
 	dev_dbg(sfb->dev, "%s: verified parameters\n", __func__);