[NETLINK]: Make use of NLA_STRING/NLA_NUL_STRING attribute validation

Converts existing NLA_STRING attributes to use the new
validation features, saving a couple of temporary buffers.

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 d0abeab..cfb527c 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -462,7 +462,7 @@
 	[RTA_PRIORITY]		= { .type = NLA_U32 },
 	[RTA_PREFSRC]		= { .type = NLA_U32 },
 	[RTA_METRICS]		= { .type = NLA_NESTED },
-	[RTA_MULTIPATH]		= { .minlen = sizeof(struct rtnexthop) },
+	[RTA_MULTIPATH]		= { .len = sizeof(struct rtnexthop) },
 	[RTA_PROTOINFO]		= { .type = NLA_U32 },
 	[RTA_FLOW]		= { .type = NLA_U32 },
 	[RTA_MP_ALGO]		= { .type = NLA_U32 },