mmc: sdhci-esdhc-imx: add MMC_CAP_1_8V_DDR for mx6

The i.MX6 supports 1.8v/3.3v eMMC DDR mode, so add this flag.

Signed-off-by: Dong Aisheng <[e-mail]>
Acked-by: Shawn Guo <[e-mail]>
Signed-off-by: Chris Ball <[e-mail]>

drivers/mmc/host/sdhci-esdhc-imx.c

···
 	if (esdhc_is_usdhc(imx_data)) {
 		writel(0x08100810, host->ioaddr + ESDHC_WTMK_LVL);
 		host->quirks2 |= SDHCI_QUIRK2_PRESET_VALUE_BROKEN;
+		host->mmc->caps |= MMC_CAP_1_8V_DDR;
 	}
 
 	if (imx_data->socdata->flags & ESDHC_FLAG_MAN_TUNING)