tests: net: socket: udp: Fix type of pointer

zsock_getsockopt() takes as last argument a socklen_t pointer
which type was changed in
c546c1c
as is not anymore equivalent to size_t.
So let's ensure we pass the right type of pointer to it.

Signed-off-by: Alberto Escolar Piedras <[email protected]>

Author: aescolar

tests/net/socket/udp/src/main.c

@@ -2492,7 +2492,7 @@ static void check_ipv6_address_preferences(struct net_if *iface,
 					   const struct in6_addr *dest)
 {
 	const struct in6_addr *selected;
-	size_t optlen;
+	socklen_t optlen;
 	int optval;
 	int sock;
 	int ret;
@@ -2573,8 +2573,8 @@ ZTEST(net_socket_udp, test_38_ipv6_multicast_ifindex)
 	struct net_if_mcast_addr *ifmaddr;
 	struct net_if_addr *ifaddr;
 	int server_sock;
-	size_t addrlen;
-	size_t optlen;
+	socklen_t addrlen;
+	socklen_t optlen;
 	int ifindex;
 	int optval;
 	int sock;
@@ -2718,8 +2718,8 @@ ZTEST(net_socket_udp, test_39_ipv4_multicast_ifindex)
 	struct ip_mreq mreq;
 	struct net_if *iface;
 	int server_sock;
-	size_t addrlen;
-	size_t optlen;
+	socklen_t addrlen;
+	socklen_t optlen;
 	int ifindex;
 	int sock;
 	int ret;