netfilter: merge meta_bridge into nft_meta

It overcomplicates things for no reason.
nft_meta_bridge only offers retrieval of bridge port interface name.

Because of this being its own module, we had to export all nft_meta
functions, which we can then make static again (which even reduces
the size of nft_meta -- including bridge port retrieval...):

before:
   text    data     bss     dec     hex filename
   1838     832       0    2670     a6e net/bridge/netfilter/nft_meta_bridge.ko
   6147     936       1    7084    1bac net/netfilter/nft_meta.ko

after:
   5826     936       1    6763    1a6b net/netfilter/nft_meta.ko

Signed-off-by: Florian Westphal <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>

Author: Florian Westphal

include/net/netfilter/nft_meta.h

@@ -8,13 +8,6 @@ menuconfig NF_TABLES_BRIDGE
 	bool "Ethernet Bridge nf_tables support"
 
 if NF_TABLES_BRIDGE
-
-config NFT_BRIDGE_META
-	tristate "Netfilter nf_table bridge meta support"
-	depends on NFT_META
-	help
-	  Add support for bridge dedicated meta key.
-
 config NFT_BRIDGE_REJECT
 	tristate "Netfilter nf_tables bridge reject support"
 	depends on NFT_REJECT && NFT_REJECT_IPV4 && NFT_REJECT_IPV6

net/bridge/netfilter/Kconfig

@@ -3,7 +3,6 @@
 # Makefile for the netfilter modules for Link Layer filtering on a bridge.
 #
 
-obj-$(CONFIG_NFT_BRIDGE_META)  += nft_meta_bridge.o
 obj-$(CONFIG_NFT_BRIDGE_REJECT)  += nft_reject_bridge.o
 
 # packet logging