staging: wilc1000: linux_mon: fix coding style of kmalloc usage

This patch fixes coding style of kmalloc usage found by checkpatch.pl
CHECK: Prefer kmalloc(sizeof(*mgmt_tx)...) over kmalloc(sizeof(struct
tx_complete_mon_data)...)
Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/linux_mon.c

@@ -163,7 +163,7 @@ static int mon_mgmt_tx(struct net_device *dev, const u8 *buf, size_t len)
 	}
 
 	netif_stop_queue(dev);
-	mgmt_tx = kmalloc(sizeof(struct tx_complete_mon_data), GFP_ATOMIC);
+	mgmt_tx = kmalloc(sizeof(*mgmt_tx), GFP_ATOMIC);
 	if (!mgmt_tx) {
 		PRINT_ER("Failed to allocate memory for mgmt_tx structure\n");
 		return -EFAULT;