brcmfmac: use kcalloc() to prevent integer overflow

The multiplication here looks like it could overflow.  I've changed it
to use kcalloc() to prevent that.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c b/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
index e40cfe8..24e8f8d 100644
--- a/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c
@@ -3297,8 +3297,8 @@
 		int i;
 
 		request = kzalloc(sizeof(*request), GFP_KERNEL);
-		ssid = kzalloc(sizeof(*ssid) * result_count, GFP_KERNEL);
-		channel = kzalloc(sizeof(*channel) * result_count, GFP_KERNEL);
+		ssid = kcalloc(result_count, sizeof(*ssid), GFP_KERNEL);
+		channel = kcalloc(result_count, sizeof(*channel), GFP_KERNEL);
 		if (!request || !ssid || !channel) {
 			err = -ENOMEM;
 			goto out_err;