msdk: change the wait time for encoder and vpp

In MSDK samples, the wait time for encoder, decoder and vpp is
300000. Let's set the wait time to the same value in msdk plugin

sys/msdk/gstmsdkenc.c

@@ -661,9 +661,12 @@ gst_msdkenc_finish_frame (GstMsdkEnc * thiz, MsdkEncTask * task,
     return GST_FLOW_ERROR;
   }
 
-  /* Wait for encoding operation to complete */
+  /* Wait for encoding operation to complete, the magic number 300000 below
+   * is used in MSDK samples
+   * #define MSDK_ENC_WAIT_INTERVAL 300000
+   */
   MFXVideoCORE_SyncOperation (gst_msdk_context_get_session (thiz->context),
-      task->sync_point, 10000);
+      task->sync_point, 300000);
   if (!discard && task->output_bitstream.DataLength) {
     GstBuffer *out_buf = NULL;
     guint8 *data =