net: restore upstream changes which break routing in tunnel scenarios

This reverts commit:

  3d78e430 net: Revert upstream changes which break routing in
          tunnel scenarios

Restored changes are:

  f1900fb5 net: Really fix vti6 with oif in dst lookups
  4148987a net: Fix vti use case with oif in dst lookups for IPv6
  42a7b32b xfrm: Add oif to dst lookups

Now it is save to restore the reverted upstream changes. Also
below upstream changes are coming with android@73a2b70 (4.4.92)
which will hit conflict if the above changes are not restored.

  c6a272aa BACKPORT: net: xfrm: support setting an output mark.
  511953db UPSTREAM: xfrm: Only add l3mdev oif to dst lookups

Change-Id: Ia34abd5b9e2625d44922c018756d2214e2bd47bf
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>