Add Microchip SAME51 Curiosity Nano board

Add Microchip SAME51 Curiosity Nano board

This board is (software wise) similar to the existing SAME54 Xplained
Pro board, with just a slightly different MCU. (Hardware wise, it
features a vastly different form factor.)

Signed-off-by: Jörg Wunsch <openocd@uriah.heep.sax.de>
Change-Id: I5e5435d49d333fb74471994ee84de59ed983153c
Reviewed-on: https://review.openocd.org/c/openocd/+/6747
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Axel W.
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>