dm: mmc: Drop the get_dev() function

This function is implemented by the legacy block functions now. Drop it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/mmc.c b/cmd/mmc.c
index c5454bf..4f25187 100644
--- a/cmd/mmc.c
+++ b/cmd/mmc.c
@@ -432,7 +432,7 @@
 	if (!mmc)
 		return CMD_RET_FAILURE;
 
-	mmc_dev = mmc_get_dev(curr_device);
+	mmc_dev = blk_get_devnum_by_type(IF_TYPE_MMC, curr_device);
 	if (mmc_dev != NULL && mmc_dev->type != DEV_TYPE_UNKNOWN) {
 		part_print(mmc_dev);
 		return CMD_RET_SUCCESS;