drm/mediatek: fix mtk_hdmi_setup_vendor_specific_infoframe mistake

commit 014580ff upstream.

mtk_hdmi_setup_vendor_specific_infoframe will return before handle
mtk_hdmi_hw_send_info_frame.Because hdmi_vendor_infoframe_pack
returns the number of bytes packed into the binary buffer or
a negative error code on failure.
So correct it.

Fixes: 8f83f268 ("drm/mediatek: Add HDMI support")
Signed-off-by: Nickey Yang <nickey.yang@rock-chips.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/mediatek/mtk_hdmi.c

@@ -1062,7 +1062,7 @@ static int mtk_hdmi_setup_vendor_specific_infoframe(struct mtk_hdmi *hdmi,
 	}
 
 	err = hdmi_vendor_infoframe_pack(&frame, buffer, sizeof(buffer));
-	if (err) {
+	if (err < 0) {
 		dev_err(hdmi->dev, "Failed to pack vendor infoframe: %zd\n",
 			err);
 		return err;