tests: Fix select group test on big-endian systems.

tests: Fix select group test on big-endian systems.

This test ensures that, when the selection criteria for a select group are
the same from packet to packet, the same bucket is always selected.
However, it hardcoded the bucket that was selected to the one that happens
to be selected with the current OVS hash function on little-endian systems.
On big-endian systems, the current OVS hash functions turns out to select
the other bucket.  That's fine (it's consistent, it just consistently makes
the other choice), so this commit fixes the problem by allowing either
bucket to be selected.

Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Aaron Conole <aconole@redhat.com>
Acked-by: Gerhard Stenzel <gstenzel@linux.vnet.ibm.com>