ofctrl: Correctly remove flows that are no longer needed.

The correct group ID to avoid requiring any particular output group when
removing a flow is OFPG_ANY.  OFPG_ALL just caused the OFPFC_DELETE_STRICT
commands to be ignored because no OVN flows output to OFPG_ALL.

Before this patch, ofctrl wasn't deleting flows when logical ports were
deleted; this fixes the problem.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Gurucharan Shetty <gshetty@nicira.com>

ovn/controller/ofctrl.c

@@ -366,7 +366,7 @@ queue_flow_mod(struct ofputil_flow_mod *fm)
 {
     fm->buffer_id = UINT32_MAX;
     fm->out_port = OFPP_ANY;
-    fm->out_group = OFPG_ALL;
+    fm->out_group = OFPG_ANY;
     queue_msg(ofputil_encode_flow_mod(fm, OFPUTIL_P_OF13_OXM));
 }