fix IP address

The following error was appearing when running LTE UE:

    inet_pton(): cannot convert -64.-74.0.2 to IPv4 network address

The allocated address by the core actually is 192.182.0.2.

On my host "char" is signed, leading to the above error (192 and 182
are seen as signed).

Let's force "ip_addr" unsigned and everyone is happy.

openair3/NAS/UE/ESM/esm_ebr_context.c

@@ -204,7 +204,7 @@ int esm_ebr_context_create(
             // etc
             case NET_PDN_TYPE_IPV4: {
               char ip[20];
-              char *ip_addr = pdn->ip_addr;
+              unsigned char *ip_addr = (unsigned char *)pdn->ip_addr;
               snprintf(ip, sizeof(ip), "%d.%d.%d.%d", ip_addr[0], ip_addr[1], ip_addr[2], ip_addr[3]);
               const char *ifn = get_softmodem_params()->nsa ? "oaitun_nru" : "oaitun_ue";
               char ifname[IFNAMSIZ];