[BRIDGE]: Lost call to br_fdb_fini() in br_init() error path

In case the br_netfilter_init() (or any subsequent call)
fails, the br_fdb_fini() must be called to free the allocated
in br_fdb_init() br_fdb_cache kmem cache.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>