mmc: Convert HI6220 MMC driver to driver model

Convert HiSilicon HI6220 MMC driver based on DWMMC IP to driver
model.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Enable this on poplar]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/poplar_defconfig b/configs/poplar_defconfig
index ea0ea89..81bd370 100644
--- a/configs/poplar_defconfig
+++ b/configs/poplar_defconfig
@@ -16,6 +16,7 @@
 CONFIG_FASTBOOT_BUF_SIZE=0x10000000
 CONFIG_FASTBOOT_FLASH=y
 CONFIG_FASTBOOT_FLASH_MMC_DEV=0
+CONFIG_DM_MMC=y
 CONFIG_MMC_DW=y
 CONFIG_MMC_DW_K3=y
 CONFIG_USB=y