mmc: Fix uninitialised priv member

When using omap_hsmmc without the device model then the allocation
of mmc->priv ends up uninitialised.

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
diff --git a/drivers/mmc/omap_hsmmc.c b/drivers/mmc/omap_hsmmc.c
index 24027f2..02970f2 100644
--- a/drivers/mmc/omap_hsmmc.c
+++ b/drivers/mmc/omap_hsmmc.c
@@ -1449,7 +1449,7 @@
 	struct mmc_config *cfg;
 	uint host_caps_val;
 
-	priv = malloc(sizeof(*priv));
+	priv = calloc(1, sizeof(*priv));
 	if (priv == NULL)
 		return -1;