clatd: fix endianness of multicast drop

This is a *critical* fix for http://go/aog/3514294
  'Drop egress multicast on clat interface'

Bug: 404457155
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: If14ef730f78c7e991842a678260dd20df607b1ec
2 files changed