mmc: add a reinit() API

For DM_MMC, the controller re-initialization is needed to
clear old configuration for mmc rescan.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index d79cdef..0727505 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -2816,13 +2816,17 @@
 		return err;
 
 #if CONFIG_IS_ENABLED(DM_MMC)
-	/* The device has already been probed ready for use */
+	/*
+	 * Re-initialization is needed to clear old configuration for
+	 * mmc rescan.
+	 */
+	err = mmc_reinit(mmc);
 #else
 	/* made sure it's not NULL earlier */
 	err = mmc->cfg->ops->init(mmc);
+#endif
 	if (err)
 		return err;
-#endif
 	mmc->ddr_mode = 0;
 
 retry: