freedreno: get cpu timestamp again after FD_TIMESTAMP

Same as commit 91a0411d2a ("turnip: improve perfetto sync_timestamp"),
but for freedreno.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18379>

src/gallium/drivers/freedreno/freedreno_perfetto.cc

@@ -264,6 +264,9 @@ sync_timestamp(struct fd_context *ctx)
       return;
    }
 
+   /* get cpu timestamp again because FD_TIMESTAMP can take >100us */
+   cpu_ts = perfetto::base::GetBootTimeNs().count();
+
    /* convert GPU ts into ns: */
    gpu_ts = ctx->ts_to_ns(gpu_ts);