boards: nucleo_f207zg: Enable automatic flashing

Flashing board nucleo_f207zg requires additional instructions
to be provided to openocd in order to enable flashing without holding
the reset button.
Update nucleo_f207zg openocd config to provide requested instructions.


Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>
1 file changed