ipv6: do not create neighbor entries for local delivery

ipv6: do not create neighbor entries for local delivery

[ Upstream commit bd30e947207e2ea0ff2c08f5b4a03025ddce48d3 ]

They will be created at output, if ever needed. This avoids creating
empty neighbor entries when TPROXYing/Forwarding packets for addresses
that are not even directly reachable.

Note that IPv4 already handles it this way. No neighbor entries are
created for local input.

Tested by myself and customer.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Marcelo Ricardo Leitner <mleitner@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>