Merge branch 'ip-ip6_gre-fix-gre-tunnels-not-generating-ipv6-link-local-addresses'

Merge branch 'ip-ip6_gre-fix-gre-tunnels-not-generating-ipv6-link-local-addresses'

Thomas Winter says:

====================
ip/ip6_gre: Fix GRE tunnels not generating IPv6 link local addresses

For our point-to-point GRE tunnels, they have IN6_ADDR_GEN_MODE_NONE
when they are created then we set IN6_ADDR_GEN_MODE_EUI64 when they
come up to generate the IPv6 link local address for the interface.
Recently we found that they were no longer generating IPv6 addresses.

Also, non-point-to-point tunnels were not generating any IPv6 link
local address and instead generating an IPv6 compat address,
breaking IPv6 communication on the tunnel.

These failures were caused by commit e5dd729460ca and this patch set
aims to resolve these issues.
====================

Link: https://lore.kernel.org/r/20230131034646.237671-1-Thomas.Winter@alliedtelesis.co.nz
Signed-off-by: Jakub Kicinski <kuba@kernel.org>