flash/nor: flash driver and cfg for SAM E54, E53, E51 and D51

flash/nor: flash driver and cfg for SAM E54, E53, E51 and D51

The new Microchip (former Atmel) series powered by Cortex-M4 looks
very similar to older M0+ powered SAM D2x at the first sight.
Unfortunately the new series differs a lot in important details.
NVMCTRL has different register addresses, moved important bits
and even changed binary command set. An universal driver for all SAM D/E
would be very complicated. That's why a new driver was derived.

Tested on Microchip SAM E54 Xplained Pro kit (board cfg included).

Adjusted for the restructured dap support.
Checked by valgrind and clang static analyzer.

Change-Id: I26c67047a552076f4b207b9b89285a53d69b4ca4
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/4272
Tested-by: jenkins
Reviewed-by: Andres Vahter <andres.vahter@gmail.com>