netfilter: Fix format string mismatch in ip_vs_proto_name()

Fix string mismatch in ip_vs_proto_name()

Signed-off-by: Masanari Iida <[e-mail]>
Signed-off-by: Simon Horman <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/ipvs/ip_vs_core.c

···
 		return "ICMPv6";
 #endif
 	default:
-		sprintf(buf, "IP_%d", proto);
+		sprintf(buf, "IP_%u", proto);
 		return buf;
 	}
 }