net/fq_impl: drop get_default_func, move default flow to fq_tin

Simplifies the code and prepares for a rework of scanning for flows on
overmemory drop.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20201218184718.93650-2-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/include/net/fq.h b/include/net/fq.h
index e39f3f8..5df100b 100644
--- a/include/net/fq.h
+++ b/include/net/fq.h
@@ -47,6 +47,7 @@ struct fq_flow {
 struct fq_tin {
 	struct list_head new_flows;
 	struct list_head old_flows;
+	struct fq_flow default_flow;
 	u32 backlog_bytes;
 	u32 backlog_packets;
 	u32 overlimit;