Add missing NULL pointer assignment after fixed_queue_free and alarm_free

Bug: 37285767
Test: Code compilation
Change-Id: I53f759ea477079b0b6aed4bcbeefb645886263d6
(cherry picked from commit 86ae6c0200347fb5734491555be4a4d59eaabfea)
diff --git a/system/stack/avrc/avrc_api.cc b/system/stack/avrc/avrc_api.cc
index f523479..2fba78c 100644
--- a/system/stack/avrc/avrc_api.cc
+++ b/system/stack/avrc/avrc_api.cc
@@ -98,6 +98,7 @@
       (event == AVCT_DISCONNECT_IND_EVT)) {
     avrc_flush_cmd_q(handle);
     alarm_free(avrc_cb.ccb_int[handle].tle);
+    avrc_cb.ccb_int[handle].tle = NULL;
   }
 }
 
@@ -116,6 +117,7 @@
 
   alarm_cancel(avrc_cb.ccb_int[handle].tle);
   fixed_queue_free(avrc_cb.ccb_int[handle].cmd_q, osi_free);
+  avrc_cb.ccb_int[handle].cmd_q = NULL;
 }
 
 /******************************************************************************