The enumeration field within the header payload should keep the
enumeration describing the header field, and not use the variant
selector enumeration.
This issue has been introduced by commit "Fix: network instrumentation
handling of corrupted TCP headers".
It causes the following warning messages in babeltrace:
[warning] Unknown value 6 in enum.
[warning] Unknown value 17 in enum.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>