cmsis_dap_usb: Support for Microchip's nEDBG CMSIS-DAP interface

cmsis_dap_usb: Support for Microchip's nEDBG CMSIS-DAP interface

This commit fixes support for the nEDBG CMSIS-DAP interface
which is used ie. on the Curiosity Nano SAMD21 board.
nEDBG, similarily to mEDBG, does not support 512 byte HID packets.
This patch adds its USB PID to the exclusion list to make sure that
we stick with the default 64 bytes.

Change-Id: I9010b0cf77c0b1347269a759b5d16ee5155abb16
Signed-off-by: Michal Potrzebicz <michal@elevendroids.com>
Reviewed-on: http://openocd.zylin.com/5756
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>