Revert "vxlan: Fix NPD in {arp,neigh}_reduce() when using nexthop objects"

This reverts commit e211e3f4 which is
commit 1f5d2fd1 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I8120874fe160a3c468eb0792f86da6fa52b5beb5
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>