ip/tunnel: always print all known attributes

ip/tunnel: always print all known attributes

Presently, if a Geneve or VXLAN interface was created with 'external',
it's not possible for a user to determine e.g. the value of 'dstport'
after creation. This change fixes that by avoiding early returns.

This change partly reverts commit 00ff4b8e31af ("ip/tunnel: Be consistent
when printing tunnel collect metadata").

Signed-off-by: Ilya Dmitrichenko <errordeveloper@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David Ahern <dsahern@kernel.org>