mmc: msm_sdhci: Set mmc->dev pointer in msm_sdc_probe()

MMC core expects (now) valid mmc->dev pointer.
During conversion in commit cffe5d86 not every driver was updated.

This patch fixes crash while accessing MMC on
boards using Qualcomm SDHCI controller.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/msm_sdhci.c b/drivers/mmc/msm_sdhci.c
index 64bbf0c..96dcdbe 100644
--- a/drivers/mmc/msm_sdhci.c
+++ b/drivers/mmc/msm_sdhci.c
@@ -136,7 +136,12 @@
 	host->version = sdhci_readw(host, SDHCI_HOST_VERSION);
 
 	/* automatically detect max and min speed */
-	return add_sdhci(host, 0, 0);
+	ret =  add_sdhci(host, 0, 0);
+	if (ret)
+		return ret;
+	host->mmc->dev = dev;
+
+	return 0;
 }
 
 static int msm_sdc_remove(struct udevice *dev)