board: Add LS1046ARDB

This adds support for the LS1046A Reference Design Board. There are
several JTAG headers accessable once the case is opened, but this config
is for the externally-accessable CMSIS DAP.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Change-Id: I0f83470da3758f0c4512ce47348c4db7de17b27e
Reviewed-on: https://review.openocd.org/c/openocd/+/6855
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>