spi: mt65xx: Don't disguise a "return 0" as "return ret"

Because of the earlier

	 if (ret)
		return ret;

ret is always zero at the end of mtk_spi_suspend(). Write it as explicit
return 0 for slightly improved clearness.
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230530081648.2199419-4-u.kleine-koenig@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mt65xx.c

@@ -1312,7 +1312,7 @@ static int mtk_spi_suspend(struct device *dev)
 		clk_disable_unprepare(mdata->spi_hclk);
 	}
 
-	return ret;
+	return 0;
 }
 
 static int mtk_spi_resume(struct device *dev)