netfilter: fix ebtables dependencies

Ingo Molnar reported a build error with ebtables:

ERROR: "ebt_register_table" [net/bridge/netfilter/ebtable_filter.ko] undefined!
ERROR: "ebt_do_table" [net/bridge/netfilter/ebtable_filter.ko] undefined!
ERROR: "ebt_unregister_table" [net/bridge/netfilter/ebtable_filter.ko] undefined!
ERROR: "ebt_register_table" [net/bridge/netfilter/ebtable_broute.ko] undefined!
ERROR: "ebt_do_table" [net/bridge/netfilter/ebtable_broute.ko] undefined!
ERROR: "ebt_unregister_table" [net/bridge/netfilter/ebtable_broute.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2

This reason is a missing dependencies that got lost during Kconfig cleanups.
Restore it.
Tested-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/netfilter/Kconfig

@@ -4,6 +4,7 @@
 
 menuconfig BRIDGE_NF_EBTABLES
 	tristate "Ethernet Bridge tables (ebtables) support"
+	depends on BRIDGE && BRIDGE_NETFILTER
 	select NETFILTER_XTABLES
 	help
 	  ebtables is a general, extensible frame/packet identification