rename RTNH_F_EXTERNAL to RTNH_F_OFFLOAD

RTNH_F_EXTERNAL today is printed as "offload" in iproute2 output.

This patch renames the flag to be consistent with what the user sees.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index e13fcc6..64c2076 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1764,7 +1764,7 @@
 			/* record local slen */
 			slen = fa->fa_slen;
 
-			if (!fi || !(fi->fib_flags & RTNH_F_EXTERNAL))
+			if (!fi || !(fi->fib_flags & RTNH_F_OFFLOAD))
 				continue;
 
 			netdev_switch_fib_ipv4_del(n->key,