Revert "neighbour: fix unaligned access to pneigh_entry"

This reverts commit 9fcc3c3d which is
commit ed779fe4 upstream.

It breaks the Android kernel abi and is not needed for Android systems,
so it is safe to revert.

Bug: 161946584
Change-Id: I0aa37ddcb0939b55d0d1b74ab3e0432b02cc5285
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>