[NETLINK]: Introduce nested and byteorder flag to netlink attribute

This change allows the generic attribute interface to be used within
the netfilter subsystem where this flag was initially introduced.

The byte-order flag is yet unused, it's intended use is to
allow automatic byte order convertions for all atomic types.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index df17aab..f823ca3 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -487,7 +487,7 @@
 	}
 
 	nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
-		switch (attr->nla_type) {
+		switch (nla_type(attr)) {
 		case RTA_DST:
 			cfg->fc_dst = nla_get_be32(attr);
 			break;