The old way to boot tiny210 was to restart barebox after loading stage2 image.
This turned out to be unstable and stopped working after barebox refactoring.
Now jump to the same position in the loaded code instead of starting it from
the very beginning.

Signed-off-by: Alexey Galakhov <agalakhov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>