netlink: specs: add ovs_vport new command

Add NEW to the spec, it was useful testing the fix for OvS
input validation.

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20230814205627.2914583-3-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>