SDIO 禁止1v8电压切换

sdhci_add_host
sdhci_setup_host
if ((mmc->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 |
MMC_CAP_UHS_DDR50 | MMC_CAP_1_8V_DDR)) ||
(mmc->caps2 & (MMC_CAP2_HS200_1_8V_SDR | MMC_CAP2_HS400_1_8V)))
host->flags |= SDHCI_SIGNALING_180;

dwcmshc_probe
sdhci_pltfm_init
sdhci_alloc_host
host->mmc_host_ops = sdhci_ops;