net: Put flowi_* prefix on AF independent members of struct flowi

I intend to turn struct flowi into a union of AF specific flowi
structs.  There will be a common structure that each variant includes
first, much like struct sock_common.

This is the first step to move in that direction.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index b5d523b..79179ad 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -563,7 +563,7 @@
 			struct flowi fl = {
 				.fl4_dst = nh->nh_gw,
 				.fl4_scope = cfg->fc_scope + 1,
-				.oif = nh->nh_oif,
+				.flowi_oif = nh->nh_oif,
 			};
 
 			/* It is not necessary, but requires a bit of thinking */