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

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.de
Signed-off-by: Mark Brown <broonie@kernel.org>