dm: mmc: intialize dev when probe

Need to initialize mmc->dev when probe, or will met
"dev_get_uclass_priv: null device", when `mmc dev 1`.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c
index 103b32e..9796d39 100644
--- a/drivers/mmc/fsl_esdhc.c
+++ b/drivers/mmc/fsl_esdhc.c
@@ -1010,6 +1010,7 @@
 	}
 
 	upriv->mmc = priv->mmc;
+	priv->mmc->dev = dev;
 
 	return 0;
 }