flash_ec: add support for SWD, nrf51, and hadoken BUG=none TEST=manual BRANCH=none flash_ec --board=hadoken flash_ec --board=npcx_evb flash_ec --board=samus Use openocd in SWD mode to flash the nRF51 chip. Use warm_reset to exit DEBUG mode. Change-Id: Iaf2827d4ce5be6d61431a3de7ab4f86aa4adde02 Signed-off-by: Myles Watson <mylesgw@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/287039 Reviewed-by: Vincent Palatin <vpalatin@chromium.org>