nrf/Makefile: Add support for flashing with a Black Magic Probe.
nrf/Makefile: Add support for flashing with a Black Magic Probe.

Also rename "flash" target to "deploy" to match other ports (but provide
"flash" as an alias for backwards compatibility).

selste/micropython,henriknelson/micropython,MrSurly/micropython,henriknelson/micropython,kerneltask/micropython,pramasoul/micropython,pozetroninc/micropython,selste/micropython,bvernoux/micropython,bvernoux/micropython,selste/micropython,selste/micropython,adafruit/circuitpython,adafruit/circuitpython,tobbad/micropython,selste/micropython,trezor/micropython,tobbad/micropython,kerneltask/micropython,bvernoux/micropython,tobbad/micropython,MrSurly/micropython,bvernoux/micropython,trezor/micropython,adafruit/circuitpython,bvernoux/micropython,pozetroninc/micropython,MrSurly/micropython,MrSurly/micropython,pramasoul/micropython,pozetroninc/micropython,henriknelson/micropython,tobbad/micropython,trezor/micropython,kerneltask/micropython,kerneltask/micropython,adafruit/circuitpython,pramasoul/micropython,kerneltask/micropython,pozetroninc/micropython,pozetroninc/micropython,henriknelson/micropython,pramasoul/micropython,pramasoul/micropython,henriknelson/micropython,tobbad/micropython,adafruit/circuitpython,trezor/micropython,adafruit/circuitpython,MrSurly/micropython,trezor/micropython