Reset on debug connect

Created by: zarubaf

OpenOCD does not reliably connect. We found a sequence that usually works:

• turn on the board;
• start up OpenOCD;
• after OpenOCD has started, but before it times out hit CPU reset button.

I suspect that this might be related to the reset of the debug module, which will reset the CPU core once connected using ndmreset. This needs to be bisected further, but the debug module should definitely be capable of resetting its harts.