target: lakemon: implement assert_reset and deassert_reset

target: lakemon: implement assert_reset and deassert_reset

We're using an I/O port reset by default. The only board currently
supported (Galileo) doesn't have SRST routed on the JTAG connector.

When using 'reset halt', we must rely on Reset Break because our
adapters don't have support for PREQ#/PRDY# signals.

Tested with Intel Galileo GEN2.

Change-Id: Ia406e31c156f8001717d5b6a08bd03f71de790d3
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Reviewed-on: http://openocd.zylin.com/4016
Tested-by: jenkins
Reviewed-by: Paul Fertser <fercerpav@gmail.com>