odp-util: Fix parsing corner case for encap_nsh() actions.

When nothing matched, the code would loop forever.

Found with libfuzzer.

Reported-by: Bhargava Shastry <bshastry@sec.t-labs.tu-berlin.de>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Jan Scheurich <jan.scheurich@ericsson.com>

lib/odp-util.c

@@ -1870,6 +1870,9 @@ parse_odp_encap_nsh_action(const char *s, struct ofpbuf *actions)
             }
             continue;
         }
+
+        ret = -EINVAL;
+        goto out;
     }
 out:
     if (ret < 0) {