cmap: Fix hashing in cmap_find_protected().

cmap_find_protected calculated wrong h2 hash which causing entries with
duplicated id inserted into the cmap.

Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2018-December/047945.html
Signed-off-by: Zang MingJie <zealot0630@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

lib/cmap.c

@@ -490,7 +490,7 @@ cmap_find_protected(const struct cmap *cmap, uint32_t hash)
 {
     struct cmap_impl *impl = cmap_get_impl(cmap);
     uint32_t h1 = rehash(impl, hash);
-    uint32_t h2 = other_hash(hash);
+    uint32_t h2 = other_hash(h1);
     struct cmap_node *node;
 
     node = cmap_find_bucket_protected(impl, hash, h1);