agm: clean up cached tkv when session close

Clean up cached tkv when session close to avoid it being sent for new
sessions.

Change-Id: If3d9a9d6b5657f4577103d24215a47d745441696
CRs-Fixed: 3090564
diff --git a/service/src/session_obj.c b/service/src/session_obj.c
index 3a79281..ff1ad33 100644
--- a/service/src/session_obj.c
+++ b/service/src/session_obj.c
@@ -1266,6 +1266,11 @@
                 }
                 aif_obj->state = AIF_CLOSED;
             }
+
+            if (aif_obj->tag_config) {
+                free(aif_obj->tag_config);
+                aif_obj->tag_config = NULL;
+            }
         }
     }
     pthread_mutex_unlock(&hwep_lock);