mmc: mv_sdhci: zero out sdhci_host structure

The mv_sdhci driver was not zeroing the sdhci_host structure it
allocates causing random access violations in parts of the mmc core
where the "ops" member pointers are checked and called if not NULL.
Signed-off-by: NMatt Pelland <mpelland@starry.com>
Reviewed-by: NStefan Roese <sr@denx.de>
Signed-off-by: NStefan Roese <sr@denx.de>

drivers/mmc/mv_sdhci.c

@@ -68,7 +68,7 @@ static char *MVSDH_NAME = "mv_sdh";
 int mv_sdh_init(unsigned long regbase, u32 max_clk, u32 min_clk, u32 quirks)
 {
 	struct sdhci_host *host = NULL;
-	host = (struct sdhci_host *)malloc(sizeof(struct sdhci_host));
+	host = calloc(1, sizeof(*host));
 	if (!host) {
 		printf("sdh_host malloc fail!\n");
 		return -ENOMEM;