Revert "neighbour: fix unaligned access to pneigh_entry"

This reverts commit 8af31193.

It breaks the Android KABI and will be brought back at a later time when
it is safe to do so.

Bug: 161946584
Change-Id: Ic05e6ecce1f072a347516cd2acb38c3330b50883
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>