soc/mediatek: add new driver 'msdc' for eMMC

Add MTK host mmc driver support.
MTK host controller supports eMMC5.1 spec.

BUG=b:177389446
TEST=emerge-asurada coreboot
BRANCH=asurada

Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com>
Change-Id: I54a7749ed167c00cd631a76af7c67c654c7bc725
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51966
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

src/commonlib/include/commonlib/sd_mmc_ctrlr.h

@@ -13,6 +13,14 @@
 #define CARD_TIMEOUT		-19
 #define CARD_IN_PROGRESS	-20 /* operation is in progress */
 
+/* MMC status in CBMEM_ID_MMC_STATUS */
+enum {
+	MMC_STATUS_NEED_RESET = 0,
+	MMC_STATUS_CMD1_READY_OR_IN_PROGRESS,
+	MMC_STATUS_CMD1_READY,
+	MMC_STATUS_CMD1_IN_PROGRESS,
+};
+
 struct mmc_command {
 	uint16_t cmdidx;