dpif-netdev: Increase MAX_RECIRC_DEPTH to 8.

In a scenario where OVN does load balancing and then SNAT with a OVS
userspace datapath [0], the recirc_depth may be greater than 6. In
that case, ovs-vswitchd might drop packets and raise warnings:

  dpif_netdev|WARN|Packet dropped. Max recirculation depth exceeded.

Increasing MAX_RECIRC_DEPTH to 8 solves this issue.

[0] https://github.com/ovn-org/ovn/blob/dd5cd73e3df1bfb1a215cb45d1e2e03eff1d049a/tests/system-ovn-kmod.at#L740

Reported-at: https://issues.redhat.com/browse/FDP-251
Acked-by: Simon Horman <horms@ovn.org>
Signed-off-by: Jakob Meng <code@jakobmeng.de>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

lib/dpif-netdev.c

@@ -99,7 +99,7 @@ VLOG_DEFINE_THIS_MODULE(dpif_netdev);
 
 #define FLOW_DUMP_MAX_BATCH 50
 /* Use per thread recirc_depth to prevent recirculation loop. */
-#define MAX_RECIRC_DEPTH 6
+#define MAX_RECIRC_DEPTH 8
 DEFINE_STATIC_PER_THREAD_DATA(uint32_t, recirc_depth, 0)
 
 /* Use instant packet send by default. */