There is a plan to build the kernel with -Wimplicit-fallthrough and
this place in the code produced a warning (W=1).
This commit remove the following warning:
  security/keys/keyring.c:248:10: warning: this statement may fall through [-Wimplicit-fallthrough=]
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
                                    (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
                n--;
                offset = 1;
+               /* fall through */
        default:
                offset += sizeof(chunk) - 1;
                offset += (level - 3) * sizeof(chunk);