native crash while skipping songs with A2DP connected

this is caused by out of bound(invalid) index, pass to AVRC_MsgReq

bug:10787111
Change-Id: I5b06c646342d0d4e9202c6e22e1c1d67275efb43
diff --git a/bta/av/bta_av_act.c b/bta/av/bta_av_act.c
index e13b41f..ada7592 100755
--- a/bta/av/bta_av_act.c
+++ b/bta/av/bta_av_act.c
@@ -664,9 +664,12 @@
             (!p_data->api_meta_rsp.is_rsp && (p_cb->features & BTA_AV_FEAT_RCCT)) )
         {
             p_rcb = &p_cb->rcb[p_data->hdr.layer_specific];
-            AVRC_MsgReq(p_rcb->handle, p_data->api_meta_rsp.label, p_data->api_meta_rsp.rsp_code,
-                                      p_data->api_meta_rsp.p_pkt);
-            free = FALSE;
+            if (p_rcb->handle != BTA_AV_RC_HANDLE_NONE) {
+                AVRC_MsgReq(p_rcb->handle, p_data->api_meta_rsp.label,
+                            p_data->api_meta_rsp.rsp_code,
+                            p_data->api_meta_rsp.p_pkt);
+                free = FALSE;
+            }
         }
     }