mmc: dw_mmc: Clear the DDR mode for non-DDR

UHS_REG should be cleared for non-DDR mode. But currently there is
no way to clear DDR mode, if it is already set once. This patch adds
clearing DDR mode for non-DDR mode.
Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/dw_mmc.c

@@ -707,12 +707,15 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		break;
 	}
 
-	/* DDR mode set */
-	if (ios->timing == MMC_TIMING_UHS_DDR50) {
 	regs = mci_readl(slot->host, UHS_REG);
+
+	/* DDR mode set */
+	if (ios->timing == MMC_TIMING_UHS_DDR50)
 		regs |= (0x1 << slot->id) << 16;
+	else
+		regs &= ~(0x1 << slot->id) << 16;
+
 	mci_writel(slot->host, UHS_REG, regs);
-	}
 
 	if (ios->clock) {
 		/*