transport-helper.c: rearrange xcalloc arguments

xcalloc() takes two arguments: the number of elements and their size.
transport_helper_init passes the arguments in reverse order, passing the
size of a helper_data*, followed by the number to allocate.

Rearrange them so they are in the correct order.

Signed-off-by: Brian Gesiak <modocache@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport-helper.c

@@ -1026,7 +1026,7 @@ static struct ref *get_refs_list(struct transport *transport, int for_push)
 
 int transport_helper_init(struct transport *transport, const char *name)
 {
-	struct helper_data *data = xcalloc(sizeof(*data), 1);
+	struct helper_data *data = xcalloc(1, sizeof(*data));
 	data->name = name;
 
 	if (getenv("GIT_TRANSPORT_HELPER_DEBUG"))