ipvs: ip_vs_proto: local functions should not be exposed globally

Functions not referenced outside of a source file should be marked
static to prevent it from being exposed globally.

This quiets the sparse warnings:

warning: symbol '__ipvs_proto_data_get' was not declared. Should it be static?
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

net/netfilter/ipvs/ip_vs_proto.c

@@ -156,7 +156,7 @@ EXPORT_SYMBOL(ip_vs_proto_get);
 /*
  *	get ip_vs_protocol object data by netns and proto
  */
-struct ip_vs_proto_data *
+static struct ip_vs_proto_data *
 __ipvs_proto_data_get(struct netns_ipvs *ipvs, unsigned short proto)
 {
 	struct ip_vs_proto_data *pd;