Added support for Microchip Curiosity Nano SAMD21 board (DM320119) under hw/bsp/samd21/boards/curiosity_nano
The nEDBG on this board requires dap_protocol be specified as SWD (changed in examples/rules.mk)
NOTE: requires entry (03eb:2175) for VID:PID of nEDBG be added to /etc/udev/rules for pyocd