[DECNET]: cleanups

- make the following needlessly global functions static:
  - dn_fib.c: dn_fib_sync_down()
  - dn_fib.c: dn_fib_sync_up()
  - dn_rules.c: dn_fib_rule_action()
- remove the following unneeded prototype:
  - dn_fib.c: dn_cache_dump()

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>