net: openvswitch: Use struct_size()

Use struct_size() instead of hand writing it.
This is less verbose and more informative.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Link: https://lore.kernel.org/r/e7746fbbd62371d286081d5266e88bbe8d3fe9f0.1683388991.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/openvswitch/meter.c

@@ -69,9 +69,7 @@ static struct dp_meter_instance *dp_meter_instance_alloc(const u32 size)
 {
 	struct dp_meter_instance *ti;
 
-	ti = kvzalloc(sizeof(*ti) +
-		      sizeof(struct dp_meter *) * size,
-		      GFP_KERNEL);
+	ti = kvzalloc(struct_size(ti, dp_meters, size), GFP_KERNEL);
 	if (!ti)
 		return NULL;