mmc: mediatek: correct the implementation of msdc_card_busy

msdc_card_busy only need check if the data0 is low.
In sdio data1 irq mode, data1 may be low because of interruption.
Signed-off-by: NYong Mao <yong.mao@mediatek.com>
Signed-off-by: NChaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mtk-sd.c

@@ -1075,11 +1075,8 @@ static int msdc_card_busy(struct mmc_host *mmc)
 	struct msdc_host *host = mmc_priv(mmc);
 	u32 status = readl(host->base + MSDC_PS);
 
-	/* check if any pin between dat[0:3] is low */
-	if (((status >> 16) & 0xf) != 0xf)
-		return 1;
-
-	return 0;
+	/* only check if data0 is low */
+	return !(status & BIT(16));
 }
 
 static void msdc_request_timeout(struct work_struct *work)