[NETFILTER]: nf_conntrack: mark protocols __read_mostly

Also remove two unnecessary EXPORT_SYMBOLs and move the
nf_conntrack_l3proto_ipv4 declaration to the correct file.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
12 files changed