net: dsa: hellcreek: Add missing PTP via UDP rules

The switch supports PTP for UDP transport too. Therefore, add the missing static
FDB entries to ensure correct forwarding of these packets.

Fixes: ddd56dfe ("net: dsa: hellcreek: Add PTP clock support")
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>