mmc: dw_mmc: fixed the wrong bit control

If mode is not DDR-mode, then it needs to clear it.
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>

drivers/mmc/dw_mmc.c

@@ -321,7 +321,7 @@ static void dwmci_set_ios(struct mmc *mmc)
 	if (mmc->ddr_mode)
 		regs |= DWMCI_DDR_MODE;
 	else
-		regs &= DWMCI_DDR_MODE;
+		regs &= ~DWMCI_DDR_MODE;
 
 	dwmci_writel(host, DWMCI_UHS_REG, regs);