[nrf51] dead yunjia's might not be dead

For those working with the nrf51 cheapo thing nicknamed 'yunjia' and wondering why half of them appear to be trash: It might be a broken uicr from flashing with openocd.

Please try to reflash ALL sections in the softdevice individually at their correct position rather than the whole hex file, and let me know if that fixes the issue.

This worked for me: https://github.com/aep/aep-nrf51_tools/blob/master/openocd/ocd_flash_hex.sh