timer: Set up the real timer after driver model is available

timer: Set up the real timer after driver model is available

When using the early timer, we need to manually trigger setting up the
real timer. This will not happen automatically. Do this immediately after
starting driver model.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>