drivers: wifi: esp_at: do not connect socket on bind(INADDR_ANY)

All connect() syscalls result in EISCONN error, since underlying
_sock_connect() is attempted to be called twice. Once from net_context.c'
bind_default() (with INADDR_ANY) as part of esp_bind() and second time as
part of esp_connect().

Do not call _sock_connect() from esp_bind(INADDR_ANY), which happens as
part of connect().

Fixes: dbf3d6e911 ("drivers: esp_at: implement bind() and recvfrom() for
  UDP sockets")
Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

drivers/wifi/esp_at/esp_offload.c

@@ -110,8 +110,14 @@ static int esp_bind(struct net_context *context, const struct sockaddr *addr,
 	}
 
 	if (IS_ENABLED(CONFIG_NET_IPV4) && addr->sa_family == AF_INET) {
+		struct sockaddr_in *addr4 = (struct sockaddr_in *)addr;
+
 		LOG_DBG("link %d", sock->link_id);
 
+		if (addr4->sin_addr.s_addr == INADDR_ANY) {
+			return 0;
+		}
+
 		if (esp_socket_connected(sock)) {
 			return -EISCONN;
 		}