secril-client: Fix RIL client token management in SendOemRequestHookRaw()

On some devices, like SM-T805 (Galaxy Tab S 10.5 LTE), the RIL client
code produces errors "SendOemRequestHookRaw: No token" due to large
amount of tokens allocated by OEM messages requiring no response from
RIL daemon (like set call audio path, set call volume, set mite etc).

The indicator of an OEM message with no response expected is:

     RegisterRequestCompleteHandler(client, REQ_XXX, NULL);

inside the RIL client message method. To prevent the token pool from
overflows, the proposed patch de-registers the token and frees its call
history if the handler for this message req_id is set to NULL.

Change-Id: Id414263bf471115797cae1a9ed628249734b9347

ril/libsecril-client/secril-client.cpp

@@ -1088,6 +1088,8 @@ static int SendOemRequestHookRaw(HRilClient client, int req_id, char *data, size
     RilClientPrv *client_prv;
     int maxfd = -1;
 
+    unsigned int check_req_id = req_id;
+
     client_prv = (RilClientPrv *)(client->prv);
 
     // Allocate a token.
@@ -1126,6 +1128,13 @@ static int SendOemRequestHookRaw(HRilClient client, int req_id, char *data, size
         goto error;
     }
 
+    // check if the handler for specified event is NULL and deregister token
+    // to prevent token pool overflow
+    if(!FindReqHandler(client_prv, token, &check_req_id)) {
+        FreeToken(&(client_prv->token_pool), token);
+        ClearReqHistory(client_prv, token);
+    }
+
     return RIL_CLIENT_ERR_SUCCESS;
 
 error: